The version that I sing is:
A poor old man was crossing the road, crossing the road, crossing the road. A poor old man was crossing the road, when along came a man with a-
Fish-and-chipped-potato cart.
(Refrain) Now, don't let that wheel of your F&CPC (Three times) run over the poor old man.

Tank-on-wheels that sucks water out of holes.
(Refrain, accumulating, F&CPC, TOWTSWOOH,)

Ruddy great red Russian rocket on rollers with rude writing written on it.
(Refrain, now three vehicles))

Accumulates like the 'Barley Mow.'

Heard it in Leicestershire long ago.
That is long enough, because you are singing on your own by the third verse. Easier if you hear it.