Derek is the owner and manager of Silent Reading, a comic book store located in North London and close enough to the Fantasy Bazaar that he considers Bilbo Bagshot to be a close competitor and rival.
Derek is a big fan of Babylon 5, to the point of firing Tim on the spot for insulting the show. He likes to keep his limited edition comics on full display at the counter, as opposed to Bilbo's policy of hiding them at the back of the shop.
Physically Derek is very similar to Bilbo, both having long brown hair in a similar style and a short goatee beard. Derek, however, is younger and slimmer than Bilbo