In medieval times the manor was the basic administrative unit. Knights held the land for the monarch and in return they gave him their military support. The knight, who might be lord of many manors and land with the rents from them, had to provide not just armour, weapons and horses but food and clothing for himself and his family and his adherents.
To support a cavalryman – and a knight's fee, a manor needed enough land to raise tithes. England had about 5,000-6,000 knights' fees and the acreage that provided the fees varied according to the quality of the land. This was the Feudal system by which the king provided himself with fighting men.
most knightly families it was natural for the sons to follow in their father's
footsteps. Sons were sent off quite young to live in another man’s ( knight)
house and to learn the art of war.
Later it became easier to substitute military service with a money payment. Over the centuries this became a Tax, levied by the king to support his military enterprises and his court and his government of the country.
In the end by what dates exactly I am unclear but I suspect by the 15th century but it could have been later knighthood became an honour However it was a privilege, which some manorial lords preferred to avoid. They chose fight instead as an esquire, which denoted a high but indeterminate social status. Esquire was a high ranking apprentice or assistant to a knight and it later became a title for a man of rank. The son of a gentleman of rank would become an esquire to achieve knighthood , being submitted, by his parents, to a form of apprenticeship with a knight, and sent away from his family at an early age to learn 'The Art of War'.
In late 17th century through the early 20th century, a village would have one principal family of gentry, owning much of the land and living in the largest house, maybe the manor house. The head of this family was often called "the squire."
Gentleman was a man with an income derived from property, a legacy or some other source, and was thus independently wealthy and did not need to 'work'. The term was particularly used of those who could not claim nobility or even the rank of esquire.
For instance I discovered that neither Sir Edward Pomeroy 1431 who married to Margaret Bevill nor his son Henry Pomeroy were knights. However Henry’s son Saintclere was knighted. (There were 2 St Cleres)