George Coster was the son of a German-born gunmaker, George Ernest Julius Coster, who left Germany to work for Alex Henry in 1869. Both Julius and George were talented gunmakers who worked for Alex Henry, and in 1886, Julius formed a partnership with a Mr. Hunter, trading as Coster & Hunter in Edinburgh until 1890. Julius continued to work independently until the late 1890s, when he moved to Glasgow and worked for Charles Ingram. Around 1920, father and son worked together as George Coster & Son. Julius died in 1927, and George carried on until 1930, when he went to work for Alex Martin. He stayed there until his retirement.
In 1993, the Coster name was obtained by Glasgow Gunmakers Ltd. (now trading as Graham Mackinlay & Co Gunmakers). Since Mackinlay states that no company records have survived, it is highly recommended that an independent evaluation be done on any Coster firearm before purchase/selling.
Some information courtesy of David Grant and Vic Venters.
Previous custom longarm maker circa 1920-1930, located in Glasgow, Scotland.