Just because you don't see people doing in Londonrz doesn't mean it shouldn't be encouraged - and the only way you are going to encourage it is to make the roads friendlier to cyclists.

I don't necessarily use my bike for a full weekly shop but I do often use it to pop down to Bell Green to get a few bits and pieces (and panniers hold a surprising amount of stuff) - going on the bike often works out far faster than using the car (and before anyone says it - I obey all traffic rules and never run the red lights)