Comet tank and Charioteer CT tank

Tank in front:
The Tank, Cruiser, Comet I (A34) was a British tank that first saw use near the end of World War II. It was designed to provide greater anti-tank capability to Cromwell tank squadrons. It was armed with a 77mm HV, a derivative of the 17 pounder, with the result it was one of the few British tanks with the firepower to challenge late war German designs. It remained in British service until 1958 seeing further combat during the Korean war. Comets sold to other countries continued in some cases to operate into the 70s.

http://en.wikipedia.org/wiki/Comet_tank

Reer tank:
The Charioteer tank officially known as FV4101 Cromwell Heavy AT Gun was a British tank destroyer, designed in the 1950s from the Cromwell tank and used to add firepower to units serving in West Germany.