You will only find cask ale in a pub (or at a really good party!). This is beer that undergoes a secondary fermentation while slumbering in the landlord’s cellar; the actions of the yeast in the cask bring forth different nuances and flavours. The beer is alive so needs to be looked after carefully with a series of arcane-sounding practices: tapping, spiling, venting, being ‘kept steady’. It takes time, effort and experience. Once a cask beer is ready, it should be drunk within three or four days — the quicker it’s served the fresher it tastes.