Maybe I'm dim,

If the premises used for this event have Public Entertainment Licenses, under current legislation, why should there be a problem?

As for the second point.
This Government have argued that pubs showing live TV football matches do not require any safety measures as a result of additional entertainment licensing permission introduced in the new Licensing Act. No pub will require any additional inspections or permissions to ensure the safety of the public who pack into places where there is no safe capacity limit and consume vast ammounts of drink (often at reduced promotion prices) and then spill out onto the streets. Not much humour in the potential for disaster in this scene is there?

There is deregulation and there is reckless stupiity - you decide.