In 1891 John Robertson took over the business and added to the reputation of Boss by inventing the famous Boss single trigger in 1894, the Boss ejector in 1898 and the light handsome over and under gun in 1909, all still very much in production today.

Boss guns have always been built to an exceptional standard and consequently they have never claimed to be inexpensive. When asked if he had ever considered a Boss, King George VI replied, “A Boss gun, a Boss gun, bloody beautiful, but too bloody expensive!”.

Boss moved to 13 Dover Street in 1908, then Albermarle Street in 1930, before returning to 13 Dover Street in 1982. In the year 2000, Boss moved to premises at 16 Mount Street, Mayfair and in April 2004 the factory was woved from the basement of the shop in 16 Mount Street to its new premises by Kew Bridge in West London.   This gives the gunmakers a lot more space with plenty of natural lighting and is much more environmentally friendly for the manufacture of guns.