180C (I had a degree symbol stashed away somewhere but I can't find it), thinking of a fan oven, is not ideal for three hours'-worth of roasting because it will dry out the breast meat. Meat is a very poor conductor of heat, so more leisurely cooking at a slightly lower temperature allows more time for heat to penetrate the bird whilst lessening the drying out. It's a balancing act. If I cooked my thirteen-pounders for three hours at 180C I can guarantee that the result would be greeted not with festive glee but with respectful silence accompanying the required manly chewing. Been there, done it, got the sweat-stained paper hat.

Over the years I've tried everything and I can only relate my own experiences. I hear what everyone else has to say, most of it is interesting but some of it is about approaches I've tried and rejected. I suppose that I've cooked sixty or seventy turkeys in my time, though I admit that a year in between is just about long enough to forget what I did right last time.