The search facility at the FSA Mutuals Public Register is pretty thorough. Turns up some results you wouldn't expect. Organisations like Manchester Tenants Limited who've been running Burnage Garden Village since 1906, or how about Old Trafford Conservative Club on Seymour Grove. Actually quite a few old Conservative Clubs are registered under the Act. The latest entry for the area was Manchester City Supporters Society Ltd, March 2007.
Some stats for Manchester and thereabouts : I&P Societies (167), Building Societies (1), Credit Unions (14), Friendly Societies (46). Doesn't include Stockport or Sale which are located in Cheshire apparently. You always need some research skills to get the best out of the data.
FSA Mutuals Public Register