So what do we think would be a suitable vehicle scale for 40mm? Would 1/48 be to small?
Mathematically a six foot tall person at 1/48 is 37.5mm to the top of the head, 1/43 is 42mm to the top of the head (based on model railway scaling 7mm to the foot).
Sculpturally of course this is a different matter, hence the varied vehicle scales used with 28mm figures.
There are few 1/43 scale models, Gramodels do a Cromwell (and a Whippet) and I heard that Pete Waterman (of disposable pop music fame) had something to go on a railway flat wagon.