When I lived in SW11 near Clapham Common I found O2 worked really well. I still have it and never had any problems in this area.

Thanks. EE's price plans are somewhat rigid so im not sure. 3 are the cheapest but there really is no point in paying them anything if I cant actually use my phone. Didn't know about the steel, very annoying!

I have EE and that is pretty good. I did have Vodaphone but found that started to drop out quite a lot and switched. To be honest I think that there isn't a perfect solution in the Northcote Road are. I was told that there is too much steel around - extensions etc. Doesn't help at all. 

I recently moved back to Clapham and there is virtually no Three signal in my home! Keeping getting cut off when trying to talk to anyone on my mobile (the other person cant hear me). What network works well in this area? In particular, for trying to have a non-wifi conversation .