Are you buying from Fortnums, or are you getting the caterers in, perhaps?
If we're doing our own, I'll chip in a bottle of violet flavoured gin, so that boiledbeetle can try it, while we cheer the boys on, possibly even as they win the girls events.
I might even organise some little sausage rolls and some salmon paste sarnies
( no expense whatsoever gone to, lol :-D )
Row, Row Row The Boat, Gently Down The Stream