After various discussion on openguides-dev, and a silence on this list when I suggested it recently, I've now disabled edits on london.openguides.org and put up a warning that content may be out of date. I've also put in a robots.txt to tell search engines not to spider the site.
Readers may be interested in another London guide running on OpenGuides,
http://london.randomness.org.uk/
Regards, Dominic.