If you go to Google's blog search and type in London Underground - there's this blog right at the top and also in the first few entries on the page, which is brill. Also with tube - right at the top as a featured blog but no entries in the main listings on the front page.
Compare with Technorati - Technorati's search by tag is rubbish - it claims I last updated my blog 24 days ago - see search by "london underground" tag. Technorati is lots better when you search without the tag - see "london underground" search - at the time of typing it has indexed the latest entry on my blog and not one from 24 days ago!!
However, most of my Technorati traffic comes from its beta blog search category "blog finder" - with "london" and "travel" being where I get most traffic from.