Yes, the two vehicles in the picture are M10 (or M10A1 depending on the power unit) Tank destroyers - Lend lease, U.S. built.
The turrets are reversed in the normal travelling mode so you can't see the main weapon, but as the very long barrel of the 17 pdr is not visible over the rear end of the vehicle, it is not the Achilles version. They still have the American 75mm gun fitted.
The unit is probably an Anti-Tank Regiment, Royal Artillery rather than a Tank Regiment. This is backed up by the beret on the guy in the tank suit which is brown rather than a 'tankie's' black one.
Alan