In reply to hawkridge812:
You would need to be able to demonstrate competence leading "adventurous routes", by this I mean multi-pitch routes, sea cliffs with abseil approaches, remote crags with long/ difficult approaches, tidal crags etc etc. The intention being that you can rock up on a meet and go climbing with another member without either of you being subject to the risks of climbing with someone inexperienced. Most members will climb a bit of sport, but the vast majority of routes where you could demonstrate the necessary competencies in the UK are Trad routes.