OK Pip - you're on. I started the thread, I confess, in jest. But the thought occurs to me - well, why the hell not? I play lots and lots of tunes and to pick one wouldn't be much of a challenge (apologies to Tootler). I think I've probably sung four traditional songs in all over the past 40 years:

The Rout Of The Blues
The Waters of Tyne
High Germany
In Good King Arthur's Day

All from my youth...

So I'll accept Pip's challenge and sing one song (none of the above, by the way) (a) unaccompanied (b) by Hallowe'een (c) with video...

May the Lord have mercy on my soul.