What tanks are in these pics?

[Soldier]

The first pic tank looks like a Churchill Mk. I
That one mounted a 40mm gun
It could be the Mk. IV which mounted a 57mm gun
It is not the Mk. VII which had a 75mm gun..

Second pic does look like a mock-up..

Last one, have no idea. It is not a WWII tank design, though.. :-)