Perhaps based on Angela Carter's 1984 novel Nights At The Circus?

Unlikely, as Keith Christmas wrote and first recorded it in 1970 on his album of the same name. In those days he was a resident performer at the Bristol Troubadour club and Angela & Paul Carter lived in the next street - they ran a traditional folk club for a while in Clifton according to the "Bristol Folk" book by Mark Jones - so it's actually possible the influence was the other way round.