This was recorded off the screen by Tony Visconti on his super8. Eagle eyed viewers will notice it's Tony on congas rather than Mickey Finn. Ed Stewart is also in shot which would suggest that this is 25 May '72 - which was previously thought to have been the date for the version which was retained by ZDF (MB in a blue Alkasura jacket with black roses motif). So, added to KAL's find from last year we now have four Metal Guru performances from TOTP, more than any other T.Rex song.
What a great find. I think this may also solve the mystery (as discussed a while ago by myself and others on here) about where the photograph came from for the cover of the Marc Bolan on Video release. We were sure it was Top of the Pops and I now think the 'shot' came from this performance.