Nope ... there are none. I thought it might be an opportunity too .. until I talked about it with someone who runs one.
He's not in London so there were no competition issues but he said that in order to make ends meet he had to work hard on his online presence and have you seen how much competition there is out there online? Of course, calling in and getting that personal service is wonderful, not to mention avoiding postage costs but someone must have worked out how many people need to live nearby and how much they need to brew?