Some time back in the 1970s, BR operated a peak-hour trip from Hull <> Beverley (1640 ex Hull) using a Transpennine (cl124) set that was "spare" between Liverpool trips. At the time these sets were in a 6-car formation including a buffet. It wasn't normal for the buffet to remain open during this side-trip but on just one occasion (to my recollection) it did. I had to use it, didn't I? Just an overpriced can of pop but, hey. This journey was scheduled at 13 minutes, and it was not advertised as a "through" service to/from anywhere else. Thus I'm guessing this was (one of) the shortest end-to-end services to carry a functioning buffet.