At last, courtesy of Virgin Media, and described here. Reading this and the gushing comment by the ‘mayor’ of London you would think that this was ground-breaking, rather than a catch-up with what is available in most mass transit systems and underground railways around the world from Cairo to Singapore (or Dubai, as in the picture).
It will be free during the Olympics and then chargeable via a business model that is yet to be determined – the post rather implies that it will be available to Virgin customers only. If true this surely merits some sort of regulatory investigation. In most other cities that I have come across there is some sort of neutral host model, where customers of all the different operators can use the coverage.