I went to the (private) Leeds Grammar School, and our alumni have always been Old Leo(densian)s - there's also a rugby club in Leeds of the same name, which was originally associated with the school/alumni, and it's mentioned in that delightful Kaiser Chiefs ditty about a night out in Leeds, I Predict A Riot...

In other words, slightly obscure, but certainly not unknown. The others, I've never heard of :)