Gingernuts,
Thanks for acknowledging that I might have some good points. I assume that means you accept they are not planning to organise all night parties.

I tend to agree that if they are intending no more than 10,000 then they should not need a licence for 15,000. But that is exactly why I have considered the example of a situation where more people are arriving and letting them in is better than shutting them out. This means that if they are aiming for 10,000 people, they might knowingly breach a 10,000 licence for the benefit of the neighbours rather than as a deliberate policy.

It actually takes quite a lot to attract more than 10,000 people to Forest Hill. Apparently in advance of Jerk chicken there was regular radio advertising across South London. That is something that Horniman has never done before, and I expect they would ever allow to happen again. It take a massive publicity machine to attract significantly more than 10,000, it is not something that just happens by accident.