John George Abbott started out managing the Barnes & Mullins factory but in 1905 he started up his own workshop. He produced mainly Banjos to begin with, including a line of Banjolele branded Monarch. In the late 1920's when he was working with his son, (also named John George but nicknamed Jack), they started making Guitars and this took over as the main business. They started making Ukuleles too at this time, but Guitars were the major product. The Abbott Guitars and Ukuleles are very well regarded, but the Banjoleles, particularly the Monarchs, are considered the best British Banjoleles of the period. 

Jack Abbott retired in the 1950's but was talked out of retirement in 1970 and made over 200 more Banjoleles for the George Formby society before his death in 1994