That's my understanding, Hamish - the problem is to get them to admit that in so many words.

Though in fact it could be a bit more extreme than this, if you go by the resposne Shambles had to one of his letters to Weymouth, when he was told:

A performance of music and dancing taking place in the open and on private land i.e. land to which the public has access only with the permission of the owner, will be subject to SS3 and SS4 of the Local Government (Miscellaneous Provisions) Act 1982 (Schedule 1), which requires a licence to be granted by the Local Authority.

And to me that looks very much as if they are saying that even if the public is not admitted, it could still need a Public Entertainment Licence. For example, if you had something happening on your own garden by private invitation, such as a party or a wedding reception.