Lincolnshire Road Car breakdown tender CFU508.
Buses Illustrated for August 1960 reported that 2103, CFU508, was a utility K type that had been converted into a breakdown tender - presumably an ECW coach body must have been fitted in the late 1940s, early 1950s.
In the background are two highbridge Bristol K's, the one on the left having been fitted with a Lodekka type grill (possibly 2134 GBE844).

Photo taken by Peter Green, c. 1960, Lincoln Bus Station