Ah! Many thanks, Chrise and Mamya. Knowing next to nothing about football, I got stuck thinking of David Ginola. Not a very satisfying puzzle, more or less forcing you to look up the list of characters.
I must be missing something. I completed it easily enough but can only see 5 thematic solutions (10, 11 and 25 across, 1 and 7 down) not 6 as in the "special instructions".