One thing that's unusual about traditional songs is that expression is as important as melody - the words have got to be doing something, they shouldn't just be draped over the melody like washing on a line. But the melody is still there: ornamentation is at the level of individual words, sitting on top of an unchanged melody line (trad. ornamentation is unlike the jazz equivalent in this respect).

I love the plainness of Shirley Collins singing the Blacksmith - it's just the melody and the speaking voice. At the other extreme, Nic Jones singing the Bonny Bunch of Roses shows how out there you can get with ornamentation and still keep the melody, just about.

But timing was the big discovery for me. In this respect Anne Briggs is a kind of anti-influence: her psalm-like delivery, with speech rhythms kept in shape by a pause at the end of each line -
O what's the matter with you my lass -
And where's your dashing Jemmy? -
is exactly what I try not to do, although it took me a long time to break with that style of singing. (A minor breakthrough for me was the realisation that Let No Man Steal Your Thyme is in 4:4 - you don't have to leave a long gap between "tender girls" and "That flourish in your prime".) And you can sing unaccompanied and nail the tempo; if you work at it you can get the expression in there as well.

In this respect I've been particularly influenced by John Kelly's Valiant Sailor - several of John's arrangements are in a 4:4 which doesn't have a trace of rock and roll about it, and this is a particularly good example. It just rolls inexorably on - it makes a great support for a song with a story. Also Nic Jones's Lord Bateman, which shows how you can get a bit tricky with the tempo without losing the inexorable 4:4 effect. And above all by the late Tony Capstick, whose unaccompanied songs - The Ballad of Accounting, the Scarecrow, Van Diemens Land - basically do all of the above.