"Could take place without an audience" is also a nonsense, although a session is probably one of the few types of music which could meet this particular requirement.

The employees of my Licensing Authority do not agree and advise that sessions are the provision of a performance of live music to audience and licensable as Regulated Entertainment. Mainly as they argue that a regular session is not 'spontaneous', so it must be a licensable performance....

As the exemption still only applies to 'performance of live music and the playing of recorded music' this advice/view/position (- but not policy -) means that 5.6.2 of the SOLP, cannot benefit anything that does take place for an audience.

And anything that didn't take place for an audience, wouldn't be licensable in the first place, as a performance of live music to andience and would have no need of the exemption.

They may need some protection from employees of the Licensing Authority claiming that the premises are being provided for the purpose of the public entertaining themselves in music and dancing and licesable as Entertainment Facilities.