I think Sparks is more likely than Eagle or Wham", although it was not one listed on the list of comics I found- but the link shows it did exist.
Wham! were 80s rather than 70s and Eagle isn't an exact match.
Rainbow was a comic and they were a band in 70s and 80s although more rock than pop
Maybe it's atrick question- maybe the children's comic was someone like Peter Glaze.
It's hard to call the best answer on this- it depends on what the setter had in mind I think.
tballrossi was also happy with Eagle at first. Wizard seems unsatisfactory to me on two counts - it was neither the exact name of a comic nor of a 70s group. I think it could be Wham! if the setter's recollection of dates of music is a bit out