London climbing gyms

I'll be in London in a few weeks for about 10-15 days. I'm trying to find a good gym that's centrally located that contains a good training setup. I've seen a few online but figured I'd get the communities take on it. Arch looks pretty good. Thoughts?

I really like The Castle. It is a bit 'out there', but the building itself is so funky as to be worth the trip out in itself, and there is alot to do there--both bouldering and routes. I've usually been able to find folks to climb with just showing up there. I've also been to Mile End--again a ways out. I had no one to climb with so just bouldered--a fair amount was pretty highball (for my distinctly low-ball tastes). Still had a good time. The only time I tried to go to the Arch they were having a comp. and it was packed, so I never was able to even look around. Very centrally located so that is a big plus. From what I recall it is bouldering only, no routes. There is also Westway--quite big I understand but never been there. There may be 1 or 2 more recently opened gyms since my last visit to London 9 years ago.

Thanks for the info buddy!