It was to be recorded in September/October of 1973 and it turned out that we weren't in the studio audience watching Les Dawson. We were on stage with Slade recording their bit of the show. It was their new song that was going to be released in December of that year. Of course it was Merry Xmas Everybody and so the 30 or so of us there, got to hear the new song 2 or 3 months before it was to become the biggest selling and most heard Slade song of them all.
After watching it on TV during the Christmas period of that year, it was almost 40 years before I saw it again on YouTube.