I think it's just a case of the fact that it's a smaller weekender than the Ceroc one's - so when X amount of people leave, it's more noticeable. At a Ceroc weekender there's so many more people there in the first place, there's still a decent amount left on Monday morning.

Plus as well there's so many weekenders going on that I think more people tend to leave earlier as they can only take so much time off work.

Another little factor for me at a Ceroc weekender is that they often keep the best DJ's till last (no slight on anyone at Hemsby!), - the last couple of sets on a Monday morning Ceroc weekender are usually classics IMHO