Steve Cradock has been Paul Weller's regular guitarist since the early 90s. Damon Minchella (the only member not from Birmingham) has also played bass for Paul in the past, and despite his fall out and split from O.C.S. in 2003, he carried on with Weller until 2008. He has also played for The Who in recent times (Live 8 being the most high profile).
Simon and Oscar have toured (and released one live album) together as an acoustic duo. Their 2004 Glastonbury Acoustic Tent set featured Steve as a special guest.
Their recording studio (also the title of their second album and short-lived own record label) "Moseley Shoals", in Moseley, Birmingham is a deliberate homage to the famous Muscle Shoals studio in America.
Dan Sealey and Andy Bennett replaced Damon Minchella in 2003 and have been a permanent fixture ever since (even playing on the "Moseley Shoals 15th Anniversary Tour", which they didn't originally record on).