"I gather the popular tune to "Sam Hall" is Johnny Cash - so can anyone help me with the English tune for it?"

Martin Graebe and Shan Cowan recently released a CD called 'Parallel Strands' (Wild Goose Records WGS 323 CD, 2005). On this CD Martin sings a song called 'Tyburn Hill' (which I've also heard him call 'Lank Hall'). It's version of 'Sam/Jack Hall' from the Baring Gould collection with a marvellous tune. The words also have an older, more Georgian feel to them than many of the versions I have heard.