Browsing through The Devil's Chariots again a sentence struck my eye - "It later became routine for new types to be preceded by a few tanks made up in boilerplate for training use." (page 135)
In the case of the Mk II and III obviously for "few" one should read "all" but the implication is that some MK IVs and Vs (and perhaps V*s) were produced in boiler plate.
Does any one have any evidence for or against this?