They are a staple of every Sunday dinner and no roast would be complete without an ample serving of roast potatoes - crispy on the outside, light and fluffy in the middle.

But whether you're a meat eater, a vegan or gluten-free, the humble tuber is delicious when roasted to perfection with the right recipe. Three chefs, Jamie Oliver, Nigella Lawson and Heston Blumenthal, have all got their own spin on roast potatoes but there's one thing they all have in common to get roasties roasted to perfection.

They key factor to a perfect roast potato is one added ingredient and how it is used: vegetable oil or animal fat, depending if you're a vegetarian or not.

To make the perfect roast potatoes, cut potatoes into even sized pieces - for an extra twist, you can even try leaving the skins on, which gives them an even crispier kick on the outside.

Then cut them into even pieces and drop them into a large saucepan of water and boil them until they're soft and tender, where a knife can easily be pushed into them.

At the same time, put 100g of duck or goose fat, or 100ml of vegetable oil, onto a roasting tray and put it in the oven at 180C until it's sizzling.

Then drain the potatoes and add them to a roasting tray, spread out evenly across the tray, and liberally roll them around in the oil/fat, and roast them in the oven, turning them every 15 minutes until golden, brown and crispy.

Nigella Lawson opts for goose fat in her roast potato recipe as she says: "Goose fat for me. But you can use other fat, it just has a very high burning point which is good, a lot of goose fat and very, very hot. Those are, and modest as it may sound, I’m sorry, the perfect roast potatoes."

Nigella even goes one step further, suggesting that potatoes should be cut in triangles, which boosts the 'surface area for getting crisp'.

She adds: "It’s how you cut the potatoes. If you imagine an ovalish shaped potato. I cut out a central triangle, so you have three smallish pieces of potato, with a lot of surface area for getting crisp."