Islington Folk Club is more central than The Old Rose and Crown, but is possibly harder to find as it is some distance from Farringdon tube station (or Kings Cross or Angel) whereas The Old Rose and Crown is only just across the road from Walthamstow Central. I wouldn't expect the tube journey to Walthamstow to take more than 30 mins from Central London and as it's at the end of the Victoria Line you can't miss your stop.

I agree with Breezy though, if you want a small friendly club which welcomes a wide range of talents, "Sharps" at Cecil Sharp House (2 Regent's Park Road - a short walk from Camden Town tube) is well worth going to.

Two more Central London clubs are "Musical Traditions" and "The Cellar Upstairs".

For a fuller list of London Folk club venues and programmes, get a copy of Folk London, or look at their online diary here