You don't even need to go to Docklands. Just wandering around the financial portions of central London used to turn up loads of open networks with only WEP as protection. I tried this awhile ago now so they may have actually put some decent protection in by now

Best results are with Lucent/Orinocco cards. I've got a couple SiteCom ones as well but they're really flakey when far away from the AP.

- Trevor