In a perfectly competitive labour market, equilibrium occurs at the point where the demand for labour equals the supply of labour. This equilibrium determines both the market wage rate and the level of employment. Firms, motivated by profit maximisation, will employ labour up to the point where the marginal revenue product (MRP) of labour equals the real wage rate. At this wage, all workers willing to work are employed, and all firms willing to hire at that wage can do so. Any deviation from this point creates either excess demand or excess supply of labour, leading to disequilibrium pressures that restore balance in the long run.
The market equilibrium can be illustrated using a standard labour market diagram, with the wage rate on the vertical axis and the quantity of labour on the horizontal axis. The intersection between the downward-sloping demand curve and the upward-sloping supply curve determines the equilibrium wage (Wₑ) and level of employment (QL1). If wages are above equilibrium, an excess supply of labour develops: more people wish to work at that wage than firms wish to hire, resulting in involuntary unemployment. Conversely, if wages are below equilibrium, firms experience labour shortages, as the number of workers willing to work at that low wage is insufficient. These imbalances create pressures that push wages back toward the equilibrium level.
However, the extent to which wages and employment adjust depends on the elasticity of demand and supply for labour. If the demand for labour is wage elastic, a small change in wages leads to a large change in employment. This tends to occur in industries where labour costs form a large proportion of total costs, where substitutes such as capital are easily available, or where the product market itself is competitive and sensitive to price changes. In contrast, when the demand for labour is inelastic, for example, in highly specialised or essential services, firms are less responsive to wage changes, and employment levels tend to be more stable.
The elasticity of supply of labour is equally significant. If the supply of labour is inelastic, as in occupations requiring extensive qualifications or training, higher wages may not immediately draw more workers into the industry. Over time, as training opportunities expand and information improves, the supply of labour may become more responsive. In contrast, in low-skilled sectors with few entry barriers, labour supply can be highly elastic, and wage fluctuations quickly affect employment levels. The interaction of these elasticities largely determines the scale of employment changes when market conditions or government policies shift.
An important theoretical development within labour market analysis is the backward-bending supply curve of labour. This concept recognises that at lower income levels, an increase in wages encourages individuals to work more hours because the opportunity cost of leisure rises, the so-called substitution effect. However, beyond a certain wage threshold, the income effect may dominate: individuals earn enough to satisfy their desired standard of living and begin to value additional leisure time more highly than further income. The result is that at very high wage rates, labour supply may actually fall as workers voluntarily reduce their hours. Although largely theoretical, this helps explain phenomena such as early retirement among high earners and part-time work among professionals who prioritise work–life balance.
While competitive market theory predicts that wages and employment will gravitate toward equilibrium, real-world labour markets are often characterised by imperfections. Factors such as incomplete information, geographical immobility, occupational immobility, and institutional influences prevent markets from clearing efficiently. For example, a construction worker in northern England may be unemployed despite vacancies in London, due to high housing costs and relocation barriers. Similarly, retraining from declining manufacturing industries into expanding digital sectors may take years, reflecting occupational immobility. These frictions create persistent unemployment even when aggregate demand for labour equals aggregate supply
In response to these imperfections, governments frequently intervene to correct market failures and to pursue wider social and economic objectives. One of the most prominent interventions is the minimum wage. This sets a legal floor below which employers cannot pay their workers. In the United Kingdom, this takes the form of the National Minimum Wage (NMW) and the National Living Wage (NLW), both designed to ensure that work provides a basic standard of living and to prevent the exploitation of low-paid labour. The policy also seeks to narrow income inequality, stimulate labour market participation, and reduce the burden of in-work poverty on the welfare system.
From a theoretical standpoint, when a minimum wage is set above the market equilibrium, it disrupts the natural balance between labour demand and supply. Firms, facing higher wage costs, may reduce the number of workers they employ or cut working hours. At the same time, the higher wage encourages more individuals to seek employment. The result is a situation where the quantity of labour supplied exceeds the quantity demanded, a condition economists describe as real-wage unemployment.
Real-wage unemployment arises when wages are maintained above the equilibrium level, preventing the market from clearing. Those willing to work at the prevailing wage cannot find employment because firms’ willingness to hire has fallen. Unlike cyclical or structural unemployment, real-wage unemployment is not caused by insufficient demand for goods and services or by a mismatch of skills, but rather by wage rigidity that prevents adjustment to the equilibrium. This rigidity can stem from legislation, long-term contracts, or institutional factors such as strong trade unions.
The scale of real-wage unemployment caused by a minimum wage depends critically on the elasticity of demand for labour. In sectors where labour demand is wage inelastic, such as social care, education, or hospitality, employers find it difficult to substitute capital for labour or to relocate production. Consequently, they are likely to absorb some of the higher costs through reduced profits or modest price increases rather than cutting jobs. In contrast, when labour demand is wage elastic, firms are more sensitive to wage changes and are more likely to respond by reducing employment, outsourcing tasks, or increasing automation.
Equally important is the elasticity of labour supply. If supply is relatively inelastic, meaning few additional workers enter the market in response to higher wages, the resulting unemployment effect may be limited. However, if supply is highly elastic, particularly among groups such as students or part-time workers, the rise in wages can attract a large number of new jobseekers, amplifying the excess supply of labour and widening the unemployment gap.
In practice, empirical evidence suggests that moderate increases in minimum wages often have smaller negative employment effects than the simple competitive model predicts. This is partly because many labour markets are not perfectly competitive. In markets characterised by monopsony power, where one or a few dominant employers have the ability to set wages below workers’ marginal revenue product, a minimum wage can actually improve outcomes. The theoretical explanation is straightforward: a monopsonist hires fewer workers and pays a lower wage than would prevail under competition. Introducing a minimum wage that is set between the monopsony wage and the competitive equilibrium wage forces the employer to raise pay while also increasing the quantity of labour employed. In this case, both wages and employment rise, reducing allocative inefficiency and improving worker welfare.
The UK labour market provides several examples where this monopsony logic applies. In sectors such as residential care, cleaning, and retail — where a few large employers dominate and labour mobility is limited, the introduction and periodic uprating of the National Living Wage have helped raise pay with minimal evidence of significant job losses. Moreover, by enhancing incomes at the lower end of the wage distribution, the policy can generate positive multiplier effects through increased consumer spending and reduced welfare dependency.
Nevertheless, the policy is not without trade-offs. Critics argue that a higher minimum wage can place pressure on small businesses with thin profit margins, accelerate automation in routine jobs, and contribute to cost-push inflation as firms pass higher wage costs on to consumers. In the long run, persistent real-wage rigidity could reduce the flexibility of the labour market, limiting its ability to adjust to shocks. For this reason, many economists advocate a cautious, evidence-based approach to setting minimum wage levels, guided by the recommendations of the Low Pay Commission, which seeks to balance fairness with employment stability.
At the opposite end of the wage spectrum, governments sometimes intervene to limit excessively high pay, especially in sectors where market forces or social pressures make wage outcomes politically contentious. Wage caps or bonus limits aim to prevent income inequality from rising excessively, to discourage excessive risk-taking, and to maintain public confidence in the fairness of remuneration practices.
One prominent example is the cap on bankers’ bonuses introduced by the European Union in 2014 following the global financial crisis. Under this regulation, bonuses were limited to 100% of an employee’s fixed salary (or 200% with shareholder approval). The policy sought to align incentives in the financial sector, curbing the short-term risk-taking that had contributed to the 2008 crash. By limiting variable pay, regulators hoped to promote more stable, long-term decision-making within banks.
However, the effectiveness of such wage caps remains hotly debated among economists. Proponents argue that they promote equity and accountability, reduce moral hazard, and prevent the social costs of reckless behaviour from being externalised onto taxpayers. They also suggest that visible pay restraint at the top can improve morale among lower-paid workers and help address relative wage disparities, which can affect productivity and motivation through the so-called “fair wage–effort” hypothesis.
Critics, on the other hand, argue that wage caps distort market signals and may have unintended consequences. For instance, many banks responded to the EU bonus cap by raising fixed salaries to remain competitive in attracting global talent. This increased firms’ long-term cost base and reduced their flexibility to adjust pay in downturns. In addition, as financial markets are global, pay restrictions in one jurisdiction risk encouraging skilled workers to relocate to less regulated labour markets, such as New York or Singapore.
Economists also question whether such policies are effective tools for improving market outcomes. High pay in the financial sector may reflect scarce human capital, productivity differentials, or the global nature of banking services, rather than simple exploitation. In this view, blunt interventions like bonus caps may generate more distortions than they resolve.
Despite these drawbacks, the debate over wage caps continues to reflect broader societal concerns about income inequality and fairness. In the public sector, governments have also used pay freezes and caps as instruments of fiscal control. For example, the UK public sector pay cap imposed between 2010 and 2017 limited annual wage growth to 1%, significantly below inflation. While this policy helped contain public spending during the period of austerity, it also led to a real-terms decline in incomes for millions of workers, recruitment difficulties in key services, and a loss of morale — all of which underscore the trade-offs inherent in wage restraint policies.
A useful example of monopsony power in the UK labour market is the National Health Service (NHS). As one of the largest employers in Europe, the NHS recruits over 1.5 million workers, including doctors, nurses, healthcare assistants, and administrative staff. In many regions — particularly outside major cities — the NHS is effectively the sole major employer of healthcare professionals. This dominant position gives it substantial monopsony power over wages and employment conditions.
Unlike firms in competitive markets, the NHS does not determine pay solely through market forces. Instead, wages are set centrally through national pay frameworks, such as the Agenda for Change system, which standardises pay across grades and roles. Although these structures aim to promote fairness and consistency, they can also limit wage flexibility and responsiveness to local labour market conditions.
For example, hospitals in London and the South East often face acute staff shortages due to the high cost of living and competition from private healthcare providers. Yet, because the NHS operates a largely uniform pay scale, it cannot always raise wages in these areas without triggering cost pressures across the entire system. This rigidity can result in persistent labour shortages, high reliance on agency staff, and increased recruitment from overseas.
The monopsony model helps explain why the NHS, despite its large workforce, sometimes struggles to fill vacancies. The organisation’s wage-setting power allows it to suppress wages below what might prevail in a fully competitive market, leading to underemployment relative to social optimum. However, it is important to recognise that the NHS’s objectives differ from those of a private firm. As a public sector employer, the NHS aims to maximise social welfare rather than profit, which means its wage decisions are influenced by fiscal constraints and political priorities rather than purely by efficiency considerations.
Government policy plays a critical role in shaping these outcomes. For instance, during periods of public sector pay restraint, such as between 2010 and 2017, NHS wages fell in real terms. This led to declining staff morale, increased turnover, and worsening vacancy rates — classic symptoms of monopsonistic underpayment. Conversely, when the government authorised above-inflation pay rises in 2023 and 2024 to address widespread strikes and retention problems, recruitment pressures eased somewhat, suggesting that wage adjustments can have powerful effects on labour supply even within a monopsonistic framework.
An additional layer of complexity arises from trade union influence. Unions such as the Royal College of Nursing (RCN) and the British Medical Association (BMA) act as countervailing forces against monopsony power. Through collective bargaining and industrial action, they can push wages closer to the competitive equilibrium, potentially increasing both pay and employment. The NHS case therefore provides a rich example of how market power, institutional structure, and government policy interact in determining real-world labour market outcomes.
From an evaluative standpoint, monopsony power in the NHS highlights the tension between efficiency and equity in labour markets. On one hand, wage standardisation promotes fairness, reduces discrimination, and ensures predictable budgeting. On the other hand, it can reduce labour mobility, distort incentives, and create inefficiencies when local market conditions differ substantially from national averages. Economists therefore debate whether reforms such as regional pay bargaining or performance-related pay could improve efficiency without undermining equity.
Ultimately, the NHS illustrates both the benefits and the drawbacks of monopsony power. Centralised wage control allows the government to manage costs and maintain universal service provision, but it also risks creating persistent shortages in key professions. As such, the NHS labour market represents a real-world compromise between the theoretical ideal of competitive efficiency and the practical realities of equity, fiscal responsibility, and public service delivery.
A trade union is an organisation that seeks to protect and improve the pay and working conditions of its members through collective bargaining. By negotiating as a group rather than as individuals, workers can achieve a higher degree of bargaining power, particularly in markets where employers hold monopsony power or where information asymmetries disadvantage workers.
In a perfectly competitive labour market, the wage rate is determined purely by supply and demand. However, when a trade union intervenes, it may negotiate a wage rate above the equilibrium level. This can lead to two contrasting outcomes depending on the nature of the labour market and the strength of the union.
In a competitive labour market, if the union successfully secures a wage above the equilibrium, the quantity of labour demanded falls while the quantity supplied rises. The result is real-wage unemployment, similar to that caused by a statutory minimum wage. Some workers benefit from higher pay, but others may be excluded from employment altogether. This situation creates a classic efficiency-equity trade-off: higher wages for the employed, but fewer total jobs.
However, in markets with monopsony characteristics, union activity can have a quite different and potentially beneficial effect. As established earlier, a monopsonistic employer hires fewer workers and pays lower wages than in a competitive equilibrium. By negotiating collectively, a trade union can counterbalance the monopsonist’s wage-setting power. If the union sets a wage floor between the monopsony and competitive equilibrium wage, both wages and employment can rise. In this case, unionisation can enhance allocative efficiency and worker welfare simultaneously — a rare “win–win” outcome in labour economics.
The actual impact of trade unions depends on several factors:
Union density (the proportion of workers who are members);
The legal framework governing collective bargaining;
The elasticity of labour demand; and
The ability of firms to pass on higher wage costs through prices.
In the UK, union influence has declined considerably since the 1980s due to legislation limiting strike action, deindustrialisation, and the rise of flexible labour markets. Nevertheless, unions remain influential in key public sector occupations such as teaching, policing, and healthcare. Recent industrial action by the Royal College of Nursing (RCN) and the National Education Union (NEU) demonstrates that collective bargaining continues to shape wage outcomes in vital public services. These cases highlight the complex interaction between economic objectives (efficiency and productivity) and social goals (fair pay and equity).