Boston Deep Sea Fisheries, later Bostonair, operated a C310 from Humberside, G-TKPZ, for a few years in the 80s and 90s. It spent a lot of time at Leeds Bradford on instrument training jollies. At roughly the same time, Howarth Timber kept a C303, G-INDC, at LBA and there was also the Ravenheat Citation, G-RVHT and Elliott Bricks Citation, G-ELOT.
Nearly forgot the JTC600 C421, G-JACK.