I thought that the song (or part of it) was written by Cyril Tawney. The Yetties recorded it years ago. To fit the tune which I know, you either have to sing the last line of the chorus as:

P-U-M-P, pump, pump, pump.
or (as Little Robyn said)
P-U-M-P, pump you buggers, pump.

There's also another verse about a policeman trying to arrest the pump.

Incidently, Little Robyn, in your comment about a certain word being used a lot, were you referring to "the old bugger" himself, the late, lamented, Mervin Vincent ? I think that Merv got the title for his exhortations to audiences to "Sing you Buggers, Sing" - it definitely used to work - the chorus singing used to be great !