Anyway -- don't you have to be "drawn" from some kind of lottery to participate in the London Marathon?

There is a lottery or you can 'buy' your way in by means of pledging a lot of cash to a charity.
This is what @bingbabe did, as you have to pay to even apply for the lottery usually ending up with a negative.

Its not ideal, and raising that kind of cash was hard.. but its a once only thing. She's not doing it again.