New LibDem chief whip Don Foster should learn when to keep his mouth shut. While topping up his legendary booze cabinet in Westminster Tesco’s early yesterday afternoon, a far from salubrious looking Foster treated himself to 40 black Superkings and a tin of Roses. Lucidly chatting with a flirty woman in a lovely grey tracksuit, Foster bragged to his mystery lady friend how he had kept the LibDems in line over yesterday’s nuclear announcement despite her claims that “it’s basically a subsidy”. It’s not really the job of chief whip to publicly agree that there were internal party ructions. Then again, that is what you get if you appoint your third choice chief…