Kid Jensen's 45                                

It's been pointed out that the drum kit in the background is that of Roger Taylor from Queen.  That would make sense of Björn's complaints about the use of backing tracks (ABBA - The Book p.114), "One day we were in Manchester for ITV with the group Queen."

Unfortunately, the episode that ABBA appeared on of Kid Jensen's 45 appears to have been wiped from the Granada archives. Only around six or seven episodes from 1974 out of the 20 or so episodes produced that year.