Only other sport i've competed in was martial arts a number of years ago, and membership of the INTERNATIONAL federation was compulsory because they are the ones responsible for regulation of rules and events, and they are the ones that promote the sport and organise international events. national federations (like UKPSF) are the ones that do this same function but at a national level, and quite frankly i think it will need to just be enforced that you must be a member to play at sanctioned events. After all what you are essentially paying for is to know that your event is going to be fair and safe. I think it's actually pretty selfish that the UKPSF put in the effort of investigating events and venues and approving them, but anybody can just waltz in and play. For me UKPSF event = UKPSF members only. The fact that they will happily insure you against injury and death is a bonus in itself!