The reason for this card was actually the team mascot, for he is a giant rabbit called Peter Burrow, a play on words for Peter-Borough. He is very famous, selling a large range of merchandise, and even having a twitter site https://twitter.com/peterburrow1934?lang=en so you can keep up with all his goings on - if you are still with twitter of course, for I am not. I have moved to mastodon.
Now several collectors, and sellers, believe this set of a hundred cards to be called "Mirrorcards", and that is rather the fault of the Daily Mirror, who put that in a huge black banner right at the top of the card, whilst relegating the actual title, "Star Soccer Sides" half way down on the left.
The cards measure 76 x 44 m/m so are counted as medium size.
There is a checklist online, at NigelsWebSpace/MirrorSoccerSides where you will discover that the final four cards are of trophies, not footballers.