Cap'n,
Unless things have changed radically in the last eight years Comhaltas has kept a very low profile in London (virtually all the branches there were either dead or in need of the last rites being read). The most active branch in the capital was in West London - unfortunately it was expelled for refusing to participate in a political fund-raising event (on the basis that the branch was made up of all denominations - and even atheists like myself). It changed its name to the West London Irish Traditional Music Association - and thrived, with support from such members as Bobby Casey, Danny Meehan, The McCarthys, John Bowe, Raymond rowland, Roger Sherlock...et al.
I agree entirely about the value of the branches, unfortunately them upstairs are carving a reputation for CCE which is, to say the least, unsavoury. I suggest you visit Brú Ború sometime and see what your money's being spent on, or maybe read the reference in Fintan Vallely's Companion To Irish Traditional Music.
The subject only became relevent to EFDSS when somebody came up with the hare-brained suggestion of organising singing competitions!
Jim Carroll