Thanx Chalky, twas actually Derek Greenhoff who told me of this - must probe him for further info, I presume he has one because a mutual friend said 'have you heard Dereks version of this' when I Played Calvin.
The IPG promos of 'Goodbye' actually credit 'Harry Starr' vocal accompaniment 'The Keyavas'
Will let you know if I glean any more info from DG - maybe even a scan!
Best
M.