This is classic nostalgia, one of my favourite all time singles free of the crackles and hiss of vinyl. Rod Stewart gives one of his finest performances, for which he originally received no credit on the 45. Find a copy of the single and you'll see: no mention of the voice's owner.
I still know nothing of the membership of Python Lee Jackson, only that Stewart was an on-off session singer at the time, and his gravelly style was perfect for the fatalistic lyric and downbeat musical groove.
A one-hit wonder, and it's still startlingly powerful. Brilliant!