Most domestic ovens these days have, as well as conventional top and bottom heat, a fan-assisted or convection function. I cannot stress this enough: avoid using the fan setting for baking. (If your oven is only fan, then reduce the temperature by 20°C/36°F and reduce the cooking time by 5–8 minutes.)
My experience has taught me that baking on the fan setting is usually when home bakers get disappointing results. Even though I mentioned this in my earlier books, people continue to use the fan and then send me pictures of collapsed cakes and cakes with a burnt top and pale bottom. Fan-assisted or convection function creates an aggressive heat, which does wonderful things for the top of your mac ‘n’ cheese but terrible things for your cake or pie. I’ve decided to put ‘do not use the fan setting’ in every instruction because many people don’t read this practical information at the back of the book, or have read it and forgotten, which is understandable.