You have to go back to the 70s for real industrial-strength Radio 2 cheese like Manhattan Transfer and Brotherhood of Man, but I have found a few more horrors from the No.1 singles list (some of them are cover versions, but more famous than the originals):
Making Your Mind Up - Bucks Fizz
The Lion Sleeps Tonight - Tight Fit
Only You - The Flying Pickets
99 Red Balloons (or Neun-und-Neunzig Luftballons, if you prefer) - Nena
Hello - Lionel Richie
It gets better by the middle of the decade, but then there's this one, which I think was banned under one of the SALT treaties:
Swing The Mood - Jive Bunny