Herr Tubthumper is right. The Cask Pub & Kitchen is probably the best pub in central London, although it may not look like much from outside, and is certainly in the top two for craft beers. Can be found on the corner of Charlwood Street and Tachbrook Street about ten mins walk from Victoria in the general direction of Pimlico tube and Vauxhall Bridge and is well worth the stroll.
It's great isn't it. I really like it.