Jason Dykes showed this at the GeoVisualisation Meeting in Oxford on August 30th: A map of road crashes in Great Britain (not the UK) from 1999 to 2010. It mirrors of course the road network and the density of population but it is a remarkable graphic.
It was made by the BBC and first published on 2nd December 2011. Apologies to those who have seen it but it resonates with quite a lot of stuff on the SIMULACRA blog including Jon Reades and Joan Serras visualisations of network traffic and flows in London and GB. There is a nice movie of all this and you can zoom into different parts of the Great Britain Map.