Mel Giedroyc and Sue Perkins host the grand final where Holly, Jo and Mary-Anne face their biggest challenge yet - baking for `The Great British Bake Off' street party. None of them have baked on this scale before. Amongst their offerings are mille-feuille, mini Victoria sponges, strawberry and cream meringue nests and miniature strawberry and rhubarb cheesecakes. Who of the three will take home the trophy?