I apologise for contributing to this thread so late, but I've been madly searching for an extant audio of this song and can't find a single thing! As a 1990s child, I used to sing along to this on a tape cassette full of children's songs (sung by a children's choir), and the lyrics were closest to the version recorded by Iona and Peter Opie, but instead with something along the lines of:

"Will you have a pint of ale? / We are the Romans? / Will you have a pint of ale for we are the Roman soldiers. A pint of ale won't serve us all / We are the British / A pint of ale won't serve us all, for we are the British soldiers. Will you have a barrel of ale? / etc. etc."

Does this sound familiar to anyone here? The tune was mostly like the MIDI file linked above, but with some differences in the notes (I can still sing it perfectly, like the cassette version I had), but I just wonder why there's nothing available that we can find, a classic children's song that is forever a golden moment in my childhood, this quiet child sitting in her bedroom playing or reading and singing along to this song which filled her imagination.