I know.
These are the most recent figures I can find for London (base tariff)
British Gas: 15.1 pence per kWh
EDF Energy: 16.0 pence per kWh
nPower: 16.2 pence per kWh
E.ON Energy: 14.8 pence per kWh (2012 increase not included)
ScottishPower: 16.8 pence per kWh
SSE: 15.5 pence per kWh
That's because those are base tariffs - they're designed to be expensive so they make money off you if you don't switch.