"No regulated entertainment" - but there's still no definition of what counts as entertainment.

And if "your local cafe for example - not serving alcohol - would not need a Premises Licence", without such a Premises Licence allowing music any musical entertainment would surely be illegal.

The "incidental to other actiuvities" might give a let out sometimes, though not one that would cover cases like the branch of Waterstones that invited a String Quarter to play, and the people then had to sit instead and listen to a record of them playing instead. But does the "incidental" exemption apply anyway to situations where there is no Premises Licence in the first place (such as a private house having a publicly accessible music evening)?