Yes, SDTL is a parody from the pen of Toby Fagenson (I think he's from the US) and I'd agree with John R - and Hilary's rendition on her latest CD is super.
Actually I've also heard Dave Kidman sing it, I think it was at Barnsley, got a great reception. He had an extra verse that fitted the shanty element too. Haven't seen him around much lately though - hope he's not been forced under ground.