The "Tank Advancing" is a Medium MkI, the "Tank Negotiating a Bank(?) is a Vickers Carden Loyd, possibly a Model 1933, the tracked vehicle pulling the gun is (hard to make out) a Dragon of some type, possibly a MkIII, there's a model in the Woolwich Arsenal, looks very much like this combo.
The Tracked Howitzer looks like something to tow behind a Carden Loyd, I've seen photos with 20 or 25mm A/T guns, as below
And a howitzer. complete with its wheels sat on the tracked trailer, but nothing like this one.