At 180°C (conventional oven): Rare — 20 minutes per kg plus 20 minutes. Medium — 25 minutes per kg plus 25 minutes. Well-done — 30 minutes per kg plus 30 minutes. For example, a 1.5 kg joint cooked to medium takes approximately 25 × 1.5 + 25 = 62 minutes. Always rest the lamb for 15–20 minutes after cooking before carving.

Use a meat thermometer inserted into the thickest part of the joint. Rare: 52–55°C (125–130°F). Medium-rare: 57–60°C (135–140°F). Medium: 63–68°C (145–155°F). Well-done: 71°C+ (160°F+). Remove the lamb from the oven 3–5°C below your target — it will continue to rise while resting.

Yes — cover the lamb loosely with foil for the first two-thirds of cooking. This keeps moisture in and allows the meat to steam gently. Remove the foil for the final third of cooking to allow the surface to brown and develop a caramelised crust. If the outside is browning too quickly, re-cover with foil until done.

Allow 200–250g of raw boneless lamb per person for a standard main course. For generous portions or hungry guests, plan 300g per person. A 2 kg boneless leg will serve 7–8 people comfortably. If serving as part of a large spread with many sides, 150–180g per person is enough. Note that the joint loses roughly 20–25% of its weight during cooking.

Rest your lamb for a minimum of 15 minutes, ideally 20–30 minutes, tented loosely with foil. Resting allows the juices — which rush to the centre during cooking — to redistribute throughout the meat, giving you a much juicier, more tender result. A larger joint (over 2 kg) benefits from up to 30 minutes of resting. The meat will stay warm enough to serve throughout this period.

The standard temperature is 180°C (160°C fan / 350°F / Gas Mark 4). For a crispier exterior, start at 220°C for 20 minutes, then reduce to 180°C for the remainder. For exceptionally tender, pull-apart lamb, slow-roast at 160°C for around 4–5 hours (covering well with foil). Fan ovens circulate heat more efficiently — reduce the temperature by 20°C vs a conventional oven.

It is strongly recommended to fully thaw the lamb before roasting for safe, even cooking. Thaw in the fridge — allow 24 hours for every 2 kg. Never thaw at room temperature. If cooking from frozen in an emergency, the joint must reach an internal temperature of 70°C for at least 2 minutes throughout, which is very difficult to achieve evenly and greatly increases cooking time. Always use a meat thermometer to confirm the centre is fully cooked.

Classic pairings include rosemary and garlic — stud the joint with slivers of garlic and sprigs of rosemary before roasting. Other excellent choices are: mint (as a sauce or rub), thyme, oregano, lemon zest, anchovies (which melt into the meat and add depth without fishiness), and Dijon mustard. A smear of olive oil with sea salt and cracked pepper before roasting helps achieve a golden crust. Mediterranean herb crusts with breadcrumbs also work well for a well-done joint.