Leo Sayer's debut album 'Silverbird' was full of good tracks and showed off his distinctive voice and unusual vocal range to excellent effect. His TOTP debut was even more striking (and happily some helpful person has put it on YouTube - not the original, I think, but very close in spirit). This was, of course, in the days when there were only two or three channels and everyone was talking about this guy in the clown suit and his mesmerizing performance. Since then he's had a well-documented decline, with occasional rediscoveries, but he has written and performed some memorable songs and I wouldn't bet against another comeback at some point.
Leo Sayer - Silverbird (Amazon)
Leo Sayer - Silverbird (Amazon)