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How To Cook A Perfect Roast Leg Of Lamb

There’s nothing quite like a roast leg of lamb on a Sunday afternoon.

It’s the perfect dish for a family gathering, and it’s surprisingly easy to cook!

Roasting a leg of lamb is a simple way to produce a flavourful and elegant main course.

In this recipe, we will walk you through the steps necessary to make a perfect roast leg of lamb.

How To Make Roast Leg of Lamb

The key to success is to start with a good quality cut of meat and to cook it slowly so that the flavour has a chance to develop.

leg of lamb in roasting tin with rosemary, thyme and garlic cloves

Remove the leg of lamb from the fridge and leave it at room temperature for about 1 hour before preparing. This will help to ensure that the meat cooks evenly.

Prepare The Leg Of Lamb Marinade

fresh rosemary thyme and garlic in oil next to leg of lamb

To begin, preheat the oven to 180C/160C Fan/Gas Mark 4.

Then, rub the leg of lamb with a mixture of olive oil, garlic, and herbs. Optionally add in some chopped onions and bashed garlic cloves.

Roast for about an hour and a half (more details on the leg of lamb cooking times below).

When the meat is cooked through, remove it from the oven and let it rest for 10 minutes before carving. This will give the juices time to redistribute throughout the meat, resulting in a juicy and delicious final product.

What Is The Cooking Time For A Roast Leg Of Lamb?

The cooking time for a roast leg of lamb will vary depending on the size of the lamb you are using.

As a rough rule, for well-done lamb cook for 30 minutes per 500g plus 30 minutes, and for a medium lamb cook for 25 minutes per 500g plus 25 minutes.

Cook at 180C/160C Fan/Gas Mark 4.

Oven capabilities do vary so check on the lamb during the cooking time to make sure it isn’t cooking too quickly.

Leg of Lamb Cooking Times

1kg 1hr151hr30

What Size Leg Of Lamb Do I Need?

The below weights are approximate suggestions for the size of lamb you should get depending on how many people you are serving.

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  • 2 people – 1kg
  • 4 people – 1.5kg
  • 6 people – 2kg
  • 8 people – 2.5kg

Should A Leg Of Lamb Be Covered When Roasting?

No, a leg of lamb doesn’t need to be covered when roasting, unless the outside is browning too quickly.

The olive oil and garlic mixture that is rubbed into the meat before cooking will help to create a flavourful and succulent final product.

roasted leg of lamb with rosemary garlic and roast potatoes

What Herbs Go Best With Lamb?

Some of our favourite herbs to use with lamb are rosemary, thyme, and mint.

You can either use fresh or dried herbs, depending on what you have available.

What To Serve With Roast Leg of Lamb?

Mint sauce on sliced roasted leg of lamb

There are many delicious sides that go well with a roast leg of lamb. Of course, the most favourite sauce is typically mint sauce, but you could also try garlic or peppercorn sauce.

Some of our favourite vegetables include roasted potatoes, green beans, carrots, and a simple green salad.

How Long Does Cooked Lamb Last In The Fridge?

Cooked lamb will last in the fridge for up to four days.

Make sure to store it in an airtight container so that it doesn’t dry out.

Can I Freeze Cooked Lamb?

Yes, cooked lamb can be frozen.

Again, make sure to store it in an airtight container so that it doesn’t dry out.

Frozen lamb will last for up to three months.

roasted leg ogf lamb with roasted potatoes

I hope you enjoy this roast leg of lamb recipe, let me know in the comments how you like your lamb!

roast leg of lamb

Roast Leg of Lamb

Prep Time: 15 minutes
Cook Time: 2 hours
Additional Time: 10 minutes
Total Time: 2 hours 25 minutes

Roast leg of lamb is the perfect Sunday or special occasion meal. Cook it slowly, covered in a fresh rosemary, garlic and thyme mariande.


  • 2kg leg of lamb
  • 3tbsp olive oil
  • 2 sprigs fresh rosemary, chopped
  • 1 sprig fresh thyme, chopped
  • 10 cloves garlic
  • 2 onions
  • Salt and pepper to season
  • Mint sauce (optional)


  1. Remove the leg of lamb from the fridge for about 30 minutes to 1 hour before you are ready to cook it.
  2. Preheat the oven to 180C/160C Fan/Gas Mark 4.
  3. Prepare the lamb marinade by combining the fresh rosemary, thyme, and 4 of the cloves of garlic (crushed) with the oil.
  4. Place the leg of lamb in a roasting tin and brush with the marinade.
  5. Bash the remaining garlic cloves and place them in the roasting tin with the chopped onions.
  6. Put in the preheated oven and cook for 2 to 3 hours, depending on how well cooked you prefer your lamb. See notes for recommended cooking times.
  7. When the lamb is ready, remove it from the oven and leave it for 10 minutes to rest before carving it.


Recommended Leg of Lamb Cooking Times

Use the below times as a guideline, check on the lamb during the cooking time to ensure it isn't cooking too quickly.

Cook in a preheated oven at 180C/160C Fan/Gas Mark 4.


  • 1 kg: 1 hr 15
  • 1.5 kg: 1 hr 40
  • 2 kg: 2 hrs 05
  • 2.5 kg: 2 hrs 25

Well Done

  • 1kg: 1 hr 30
  • 1.5kg: 2hrs
  • 2kg: 2 hrs 30
  • 2.5kg: 3hrs

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