Although I notice that the Deli Spicy Veggie Sandwich might well be vegan if served without the repulsive mayonnaise. The allergen information says it contains eggs, but the only egg I can find is in the "Cool Mayo". I might well email McDonalds and check, because there's avoiding McDonalds for ethical reasons on the one hand, and starving because Olympics officials didn't bother to consider vegans on the other. Oh, you can take in food as long as it's not an "excessive amount", but you're also only allowed to bring in "one soft-sided bag" (see here), so there's a limit to the amount of food that is feasible to carry. Given the number of extra layers I need to stay warm in the evenings, I'll be left with emergency protein bars and fruit...
If you want a real laugh, try Ask London 2012, for vague, meaningless answers. I've already clicked on the "I still need help" thing because of the uselessness of their "Can I bring an empty water bottle through security, and if so, will there be somewhere to refill it inside your venues?" question. Great, you can bring in a plastic bottle - up to what maximum size? The Download Festival information had wording like this, and we got there to find out that only 500 ml bottles were allowed. Which is bloody annoying for the carer of a disabled person who drinks a lot of water.