Never seen any forks quite like those. The frame is most likely 1950's given the lugs and I wondered if Bill Hannington might have built it though the frame number is 5592 - a high number and possibly built 1955. Someone at Berkshire Cycles remembered the shop at Cemetery Junction having a workshop at the back so it could have been built in house. With your frame the number could be a casting number on the BB, might be worth a look on the rear dropouts and of course, the steerer tube.