This first clue here was a bit obscure, but it was the clothing, for one of the nicknames of the Celtic Football Club is "The Hoops", and that concerns their green and white jersey. In fact at first they played in an all white strip, but then, in 1903, they changed to a green and white one, which might be considered to be striped, but is technically considered to be hooped. I believe that this comes from the fact that a stripe is straight, whilst a hoop curves at the edges to make a continuous circle, as it does around the body.
Here we have William "Billy" McNeill MBE, born on the second of March 1940. He was the obvious choice for a card for Celtic, as he had so much connection with them, over sixty years during which he was a player, a captain, a manager, and a coach - as well as being at the helm when the team won the European Cup in 1967. It is most fitting that he continues to lift that cup as a statue outside their stadium, though perhaps it is a belated apology for the way he felt he was so underappreciated by the team in the 1980s.
This set appears first in our British Trade Index part III, as :
Football Quiz. 76 x 56. Nd. (84) ... ANF-13
And its not much different in our updated British Trade Index, except that the date of issue has been added before the measurements, and there is a new card code.
I can, however, give you some useful links, courtesy of Nigel`s WebSpace; a Set gallery of all the cards - plus a Set checklist and a Team checklist.
We also know, thanks to the Trading Card Database/AFQ that these were issued with bubble gum, and the brand, "Bubbly" - also that the packets were retailed at 3d. each. This brand was introduced in 1932, and it is a single thick piece of pink bubblegum inside a wrapper, curled round and twisted to the left and right of the piece. Today we also appreciate that it is made with natural colours and flavours.
As to why it was pink, well that was the only food dye the factory had in stock at the time. Just a lucky coincidence.
Another interesting fact is that the "Bubbly" brand is now owned by Barratt - so if you order them online you need to look for Barratt Anglo Bubbly.