At the ripe old age of 90, Dame Mary Berry is as sharp as a chef's knife and busier than ever. And now, the Cordon Bleu-trained icon has shared the three no-nonsense food rules that keep her glowing, energetic and able to whip up a flawless lemon drizzle cake without breaking a sweat. Dame Mary, known for her refusal to accept a soggy bottom during her stint as a Great British Bake Off judge, is starring in a new BBC series, Mary at 90: a Lifetime of Cooking. To coincide with the series, there'