3. Place a roasting tray in the oven with the beef dripping, oil and butter and when hot and sizzling, tip in the potatoes. Roast for 40–45 minutes.

As demonstrated on James Martin's Saturday Kitchen series, here's what you'll need: 10 large King Edward potatoes, peeled, cut into large chunks 50g/13⁄4oz lard, dripping or vegetable oil ...

Roast potatoes are a staple of any Sunday roast, but getting them perfectly crispy on the outside and soft and fluffy on the inside can be difficult - luckily James Martin has a foolproof method.