You've got to write back to them and ask for the exemption, based on McGrath's idea. Actually, to satisfy the requirements, you can specify that the performances are incidental to an event at the pubs etc. The event may be happy hour, or even special "Morris Nite", which consists of nothing more than your performances. If one were inclined, one could argue also that, since the event does not involve admission or any sort of fee or restriction of attendence, (that is to say, attendence does not require any permission of the owner of said property) then the statute does not apply.

Best to present the arguement first, and, if the powers that be agree, get a letter from them.