Because ovens do vary in spite of what the temperature gauge may say. If in doubt pop a thermometer in and it will tell you precisely what the reading should be. If your oven is not correct you can call the manufacturers to get it checked and adjusted.
Win 1 of 3 Cath Kidston Tea Sets
Celebrate British National Tea Day on April 21st by entering our competition to win a quintessentially British Cath Kidston tea set