This is a big tune from a very big dude. Demis Roussos is an ethnic Greek via Egypt who played in a bunch of bands including the prog rock group Aphrodite's Child. Fellow bandmate, Vangelis (whose full name is Evangelos Odysseas Papathanassiou for those of you keeping track) arranged this and may other of Demis' tracks.
I have added Who by Odyssey, which is the original version of the track. Odyssey was a one off project featuring Vangelis.