My telling of the Williams Bros story, also a little different to existing versions:
The story of "Williams Brothers", well known in the Australian motor trade, begins with the three original Williams brothers:
George Harold Williams
Henry James Williams
William Arthur Williams
The brothers acquired the NSW branch of the Canada Cycle and Motor Agency, 625 George St, Sydney, in 1905, taking it public in 1906 as the Canada Cycle and Motor Agency, Ltd. In 1910, two other motor businesses were acquired and the combined entities re-incorporated under the same name. A magnificent seven-storey building was erected at 822 George St to house the new firm.
In 1911, the Canada Cycle and Motor Agency, Ltd, acquired the agency for Douglas motorcycles.
In 1913, the brothers took control of the bicycle and motorcycle business of the Canada Cycle and Motor Agency, Ltd, and reformed it under the name Williams Bros. The new business traded initially from the Canada building at 822 George St, but it was gutted by a massive fire in December 1913, and Williams Bros re-established at 213-217 Elizabeth St.
Enter the second generation of Williams brothers:
David Reginald 'Reg' Williams
Percy Harold Williams
Presumably they were the sons of one of the original Williams brothers, but I've yet to discover which one.
In 1914, Percy and Reg opened a motor garage in Murray St, Orange, regional NSW. After the war, the brothers combined to enter the trade in Sydney. P & R Williams, 80-82 Wentworth Ave, Sydney, opened on April 7, 1920, initially selling second-hand motorcycles. Soon they gained, from Williams Bros, Ltd, the agency for AJS motorcycles, leaving Williams Bros with the busy and lucrative Douglas agency they had held since 1911. P & R Williams was incorporated as P & R Williams, Ltd in 1922; a subsidiary of Williams Bros, Ltd.
Williams Bros, Ltd, and P & R Williams, Ltd, traded separately for the next few years. Motorcycle-wise, Williams Bros focussed on Douglas (and their own brand Waratah), and P & R Williams focussed on AJS.
In 1927, S. A. Cheney bought a controlling interest in Williams Bros, Ltd, thus also gaining control of P & R Williams. He made it clear his interest was in the motor car side of the business, mostly the Morris agency, and a major restructure followed, resulting in "the biggest motor-cycle deal in the history of the trade in Australia". A new company was formed: Williams, Ltd, under the control of D. R. (Reg) Williams, to manage the agencies for Douglas, Waratah and Sunbeam. P & R Williams, Ltd, with P. H. Williams as managing director, carried on as before with the AJS and Velocette agencies.
To give an idea of the scope of the businesses at the time of the restructure in 1927, S. A. Cheney launched legal action against Williams Bros. claiming 250,000 pounds in damages over issues to do with his purchase of shares.
The Waratah motorcycle began with the Canada Cycle and Motor Agency, Ltd, in 1911, moved to Williams Bros. in 1913, and stayed with them through the 1920s. By the early 1930s P & R Williams had taken it on, and it stayed there until the end around 1953.