I find it bizarre that either a supermarket or council could offer cheaper than an energy company! To be fair, ours was part of a "collective switch" which has now closed, but it's definitely worth signing up.
Mind you, I'm pi55ed of with BG for not believing that our 12 year old house hasn't...
Good bounce. We just switched from British Gas to Sainsburys for both fuels, and expect to save the same. See http://www.moneysavingexpert.com/utilities/you-switch-gas-electricity for details.