For the fluffiest centre, you need to begin with the right potato. I usually plump for large (200g-250g) Maris Pipers or King Edwards, which are easy to find and offer a wonderful, soft interior and crispy skin when baked well. I’m also keen to try the new Nemo potato, which is said to cook more quickly than traditional types and is stocked exclusively by Tesco. It’s also worth keeping your eyes peeled for a British variety called Orchestra, which has a lovely creamy flesh and is the current baking potato offered by M&S.
If, however, your options are limited or you’re not sure what varieties you’re picking from, any white all-rounder is generally a safer bet than a red-skinned spud, which has a higher chance of having a firm, waxy flesh rather than the floury, airy texture that defines a great jacket.