http://www.mirror.co.uk/news/uk-news/hms-ocean-sails-into-the-capital-for-olympic-818230 (http://www.mirror.co.uk/news/uk-news/hms-ocean-sails-into-the-capital-for-olympic-818230)
I was just surfing t'internet to confirm some information about the River Thames Flood Barrier, and happened upon an article from the Daily Mirror (May 2012) regarding HMS 'Ocean' sailing up the Thames in preparation for the London Olympics.
I'll let their picture do the talking...
(http://s20.postimg.org/6g98to8el/HMS_Ocean.png)