That's good, the Con Tempo quartet! When they start hitting posh music events, it brings in people with political and media muscle. Like the Pope and Prince Charles. (Well the Pope used to sing Folk Songs - and I can just imagine Prince Charles in a Morris side...)

Though in fact they've a much stronger case for saying this event was public entertainment, because it obviously was, and in a bookshop there actually could be public safety issues.

What we want is a string quartet that wants to play for fun in a pub or a cafe, and that gets shut down by the jobsworths.

As you point out Shambles, under the present law, if playing for free in public counts as public entertainment, than a PEL is required for even one person singing or playing or dancing pretty well anywhere outside their home. (And you'd could well even need one in your own garden.) Pubs with two performers allowed are actually less restricted than the rest of the country is.

It's a grotesque law, and is therefore almost certainly illegal, I believe. But then that's all been said, time and time again - however I say it again because most people won't have read all the threads, and might be under the assumption that this is primarily about what is allowed in pubs.