John Dallas started making his own Banjos in London in 1875. In 1905-6 the three sons of John E. Dallas were given directorships and the firm's title changed to John E. Dallas & Sons. John E. Dallas himself, died in 1921 and in August of that year the firm became a private limited company. 

By the late 1920's the Banjos and Banjoleles were truly mass-produced and started to use the brand names of Jedson and Mastertone, (a lot of which were manufactured by George Houghton & sons as their own manufacturing facilities appear to have been becoming less important). In this period Dallas was also one of the biggest musical instrument distributors in the UK, (and the then Empire), selling a lot of central European made instruments into this market using both their own, and the original brand names with the JED and Mastertone catalogue of 1930/31 running to 140 pages. The 1938/39 was down to 77 pages though and in this publication the Jedson brand had disappeared. With the outbreak of World War II, Dallas ceased to make banjos, (if they hadn't already). 

In 1947 John E. Dallas & Sons Ltd. became a public company and they started selling the inexpensive GH&S made banjos under the Jedson brand again. In 1963 GH&S closed down and some of the former George Houghton employees set up workshops for the Dallas company at Bexleyheath, Kent and continued to make Banjos for a while longer. After this they did sell Musima made Banjoleles, (the ones with the George Formby branding). 

In the early 1960s, the company name was changed to Dallas Musical, Ltd and in 1965, Dallas acquired Arbiter Electronics from J. and I. (Ivor) Arbiter, (aka Arbiter-Weston) and in approximately 1967 Dallas Music was merged with Arbiter Electronics, making Dallas Arbiter, Ltd. As well as distribution this company was also making amps and effects pedals under the brand name of Sound City and produced Drums, Guitars and Basses under the Hayman brand. The firm finally went out of business in 1975 but since then a new firm making Guitar effects pedals has started up called Dallas Musical Instruments London and though it likes to link back to the original firm I can see no real connection. 

While they were in production, in addition to Jedsons, Dallas sold 5 Styles of Dallas Banjolele from A, (the most basic with 8 tensioners and no extended resonator and probably, along with most if not all of the Jedsons actually made by GH&S), through to E, (the best quality and the most embellished), and as Dallas were endorsed by the British Banjolele star George Formby they put his name on the headstock, moving on to his name and picture. (the final models of the George Formby branded Banjoleles were made in East Germany by Musima and the headstock logo had gone back to just a signature).

In addition to making their own branded Banjos, they were the firm behind most of, and distributor for all of the Alvin Keetch Banjuleles and other instruments, (It is possible that GH&S made some the most inexpensive models of this rage too, and is certainly the case that the final X range was made in Germany)

Dallas also branded and sold wooden Ukuleles under the Jedson and other brand names. In the 1938 Dallas Catalogue it lists them selling Ukuleles under the brand names Pearl, (nothing to do with the later Japanese range of Drums with a few Guitars on the same name) Avalon, (nothing to do with the Staldmair Avalons) and Radiotone. I'm not sure if they made any of them in their factories though, and as well as the brands already mentioned, Dallas was the UK Distributor for, if not the owner of Manuel Lopéz Ukuleles, (but these didn't feature in the 1938 Catalogue because the Spanish Civil War had ceased production by then).

Post WWII Dallas was involved with importing instruments from east and west Germany and the Far East into the UK using some of the old names like Jedson along with the distribution of British and European instruments. I have also seen the names Torre and Kumali used to brand Ukuleles and other instruments imported by Dallas in this period.