Note as the record performed by Session Musicians, by BBC agreement , all backing vocals and music had to be perfomed by the BBC Orchestra and The Ladybirds. Hence the only Vocal(*) is Roger Greenway (the entire performance possibly mimed to tracks laid down earlier in theday).
So the entire performance differs in some aspects to the record.
Biff's explaination might be true, as I cannot recall whom took lead on the record, I suspect they had to nominate to BBC whom would carry the vocals- or it could have depended on the original session fee or contract.
Evolved from The Flower Pot Men this slice of Cook - Greenaway pop proved to be a smash. Very catchy.
Lead vocal was Tony Burrows but oddly for this Top Of The Pops performance, Burrows is seen on backing vocals whilst Roger Greenaway takes the lead. It is suspected this was down to Burrows being seen often at this time on the show as lead vocalist of Brotherhood of Man (United We Stand) and Edison Lighthouse (Love Grows) All three discs were hits at the same time!