Hi,
The Honourable Artillery Company (HAC) - a Territorial Army unit
consisting mainly of old-boys from the English public school system - were on a route-march,in 1914/5 England,
and were heard to sing a song which is normally sung "Who were you with last night, under the pale moonlight...."
in the,then, more grammatically correct way: "With whom were you with last night under the pale moonlight...."
A bit of a mouthful and not what the lyricist wanted me thinks.
Cheers, Colwyn.