But they do have a direct strategic interest in keeping the next election as tight as possible (leaving aside the baleful effect of the boundary changes on a number of their MPs) because it maximises their chance of a hung parliament in 2015 and leverage over the next government.

BBC: Reading the signs

The origin of this effect may lie at the boundary between the mantle, made up of viscous rock that extends 2, 900 km (1, 800 miles) below the crust, and the outer core, which is thought to be liquid iron with the consistency of water.

BBC: Earth's wobbles reveal deep secrets