The season of peace, goodwill and monster-sized turkeys is upon us. Getting the turkey right is the one task all cooks dread. In fact, it is all down to timing. Following cooking instructions usually leaves me with a bird that’s so dull and dry it’s inedible. So, for advice, I turned to Gerry Rae, Master Cook at Simpsons on the Strand in London, where they have been serving perfectly roasted meat for more than 150 years.