mushroom - //that's maybe what he became after the break up of T Rex, but at the time of his death he'd just completed a successful TV series for Granada (Marc), was as fit and trim as he'd been in his heyday and looked to be on the verge of a comeback. //
I think the passing of time may have coloured your memory in an over-positive way.
There is one memorable clip of Bolan - looking bloated and glassy-eyed, introducing a band and sniffing loudly the last toot of coke he had ingested in the seconds before the red light came on.
His career was on the skids, his band was gone, he was a coke head, and his further slide into obscurity was halted only by his tragic death, leaving the legacy of the fabulous music he created at his artistic peak, sadly long behind him by the time of his TV show.