Sorry Barry not that oneGreat question but I've not a clue! wild guess How to Create a Monster.
Not that I recall Leighhas it anything to do with treacle?
Close Barry but no CigarIf Adrian is allowed two guess I'll have a second one too
Forked Lightning?
Well out of the two you got the correct answer, it was the Inventor of The Forty Foot Ferret, well doneIt sounds like an early episode with Blamire.
I would say either
Inventor of The Forty Foot Ferret or
Ballad for Wind Instruments and Canoe