Bob, my musical ability is poor so, when I recognise that I have stolen a tune, and I don't want it to be known I change it here and there until it sounds sufficiently different.

My biggest problem arises when I don't know where the tune comes from. It's just there, and after I've played it a few times it sounds so familiar that I'm scared that someone will recognise it.

Then there are tunes that it's OK to use. How many songs are there that use Villikins and his Dinah? No one seems to mind.

Bert.