Heat oven to 190°C/170°C fan/gas 5. Cut small pockets into the skin and flesh of the leg of lamb by piercing it with the point of a sharp knife. Stuff each pocket with a slice of garlic, using 3-4 of the cloves, and a few springs of rosemary. Season well and leave to one side.

Melt half the butter in a large frying pan. Fry the onions, stirring frequently, until softened and golden. Add the remaining chopped garlic and rosemary and cook for a further few minutes with plenty of black pepper. Tip into a large roasting tin and toss with the sliced potatoes, carrots, thyme, flour and more seasoning.

Pour the stock into the frying pan, then add the Worcestershire sauce and the remaining butter. When melted and boiling, pour over the potatoes, cover with foil and bake for 50 minutes.

While the potatoes are cooking, heat the frying pan once again and add a drizzle of oil. Once hot, seal the leg of lamb on its fat side until golden brown (this will take roughly 6-8 minutes). Turn the lamb and cook for a further 4-5 minutes.

Uncover the hotpot and place the sealed lamb on top of the potatoes. Cook for a further 50 mins (uncovered) until the potatoes are golden and cooked all the way through and the lamb is pink. Allow the lamb to rest for 15 mins before carving. Leave the potatoes in the oven (covered if starting to brown too much) until ready to serve.

Cut the hotpot into 8 and lift onto warmed plates. Carve the lamb into thick slices and place on top. Serve with steamed green beans and mint sauce, if you like.