Preheat the oven to 425° and position a rack in the lower third of the oven. In a large shallow bowl, whisk the flour, baking powder, baking soda and fine salt.

Fold excess parchment over potatoes and cover pan with aluminum foil. Bake at 350°F until potatoes are tender, about 2 hours. Remove foil from pan, leaving parchment in place.

With Environment Secretary Elizabeth Truss admitting she regularly eats food that is past its 'best before' date, FEMAIL reveals the ten foods which can safely be consumed by all.