Regarding permissions etc - it was my wife who did it for Liverpool.

Liverpool 1 is private property so that had to be cleared through their events organiser. Partly to ensure no clashes with other events.

Church Street is public so that was the Liverpool 08 office which is effectively a city council org.

In both cases, to get the permit or licence is two weeks or so lead time, public liability insurance cert, at least one first-aider cert and a lengthy description of what the event is. Loads of rules like no leafletting.

There is a case for saying it could be a spontaneous outburst from musicians who just "happened" to be in the same area at the same time "Honest gov!" but if the worst came to the worst that wouldn't stand any level of forensic enquiry.

Not many of us would want to be labelled a felonious melodeon player, or a banjaxed banjo player, well, not more than they are already, so getting the permissions and insurance was seen as important.