"....that for a game of soldiers": Origin, please?

[James Mullan]

On moving to England several decades ago, I encountered the somewhat quaint
expression, seemingly used there only:

"[insert preferred expletive] that for a game of soldiers", such as in the
following example:

Q. "Are you going to (say) Coventry to watch the football match?"
A. "[insert preferred expletive] that for a game of soldiers, Coventry's a
dump, and their team are a bunch of wankers".

I've since wondered about the origin of the term, and ask for earliest
references, original usages, pointers, please, if such be available.
TIA
Jimmy