"October Song" is my favourite song bar none (coincidentally I was born in October but I think I first bought the album with the song in February 1973), but having heard several cover versions, to my mind nothing beats the original song on the Incredible String Band's 1st album in 1966 (when Williamson and Heron teamed up with the now deceased Clive Palmer, though this was the only ISB album Palmer played on until they re-formed briefly around the turn of the 20th and 21st century). I haven't heard of Robin Williamson having any siblings, but seem to remember reading (probably in the USB Fanzine "Be Glad") that (a) His father came from County Armagh in Northern Ireland, the county I live in (b) His mother's maiden name was MacGillivray). I remember after I performed the sing (unaccompanied as I do not play the guitar, etc) at a local Open Mic, someone claimed it was written by an Irish musician (it may have been the Pat Kilbride mentioned above) though he later conceded that it was by Robin Williamson.