In reply to Iamgregp:
> The Reach is also really good for routes (loads of Autobelays), but maybe slightly less so for bouldering and is in an area that's pretty bad for transport links unless you have a car.
The Reach is 10 mins walk from Woolwich Dockyard station, so no biggy. Worth considering, just for the sake of variety. 5 bouldering areas (inc. Cave and Comp Wall), traverse wall, plenty of lead, autobelays and TR, the training room is ok but coffee is always pretty good. A big place with nice staff and a slightly more mature membership.
I'd agree with Stronghold. It's one of the few places that always impresses me. Setting has a feel of climbing outdoors and the walls are very well shaped to aid this.
I'm surprised no one has mentioned Mile End. The original and the setting is perhaps up with the best in the country (based on hearsay and my humble experience).
The Arch is ok, but can get crowded and the setting seems to be hit and miss, with a focus on strength over technique with more comp style problems than a wall needs. That said, one of their best setters left before lockdown.
The Castle always seem to disappoint. It's as though their crushing setters have no idea what below f6C/+ means and and as such I never find any technical challenge below those grades. I can't speak of the roped activity but I've found it very cliquey compared to other walls.
I'm unsure which is the original Vauxwall (east perhaps?), but it is the worst wall I've ever been too. Setting quite poor and uninteresting and dirty holds. I have been told the newer one (vauxwest?) is better.
Further out of London, if you fancy exploring, you can find two very good bouldering facilities, Chimera in High Brooms, nr Tunbridge Wells (1 hour train from London Bridge) and The Climbing Experience in Maidstone (a newish huge facility that improves with every visit) yoga and other classes, slackline, a licensed bar and good cafe. I think it has the largest Bouldering on offer in the south east plus a fun wall if you have kids.