I have to thank Brian Kelly, as so often, for this song. He gave me a faded photocopy of the melody and lyrics in March 1993 as he himself couldn't do anything with it. I assume the copy is from a North English chap book but I can't tell for sure. Anyway the document I possess says that "..this song was written by Ewan MacColl for a recent (your guess is as good as mine) radio ballad on the theme of "Romeo and Juliet", transposed to a London setting."
I find it a very witty, clever, tuneful and gentle song on the age old theme of love and that the ladies are always 3 million light years in front of the gents when it comes to gauging the end of a love affair.

Lyrics