Quick Answer
Most UK recipes we compared roast a 2kg bone-in leg at 140 to 160°C fan for about 4 to 5 hours, covered with foil and a little liquid, until a fork pulls the meat from the bone. Slower recipes run for 7 hours or more at 120°C. Rest the lamb for 15 to 30 minutes, then make gravy from the tin.
Key Takeaways
- Decide what you mean by slow roast before you pick a recipe. A carvable joint (one UK butcher’s boneless leg: 140°C for 3½ hours, lifted at 60°C for medium) is a different dish from lamb that falls off the bone, which needs longer and a much higher centre temperature.
- Cover it, with a splash of wine, stock or water in the tin, then uncover briefly to brown. Most recipes do this, though one UK recipe roasts uncovered for 4 hours.
- Times are a guide. The recipes we read do not give a time per kilo, so test with a fork from about 3 hours, not the clock.
Slow roast leg of lamb: the simple method
A slow roast leg of lamb is a low oven, a long time and a bit of liquid. The aim is to melt the connective tissue, so the meat turns tender enough to pull apart. The recipes below disagree on temperature, timing and covering, so the table shows what each one does. We have not cooked and photographed this ourselves, so none of the timings are our own test results.
Slow roast leg of lamb temperature and time: what UK recipes say
| Recipe | Joint | Oven | Covered? | Time |
| Sainsbury’s Magazine, with fennel | 2 to 2.25kg | 200°C (fan 180) for 30 minutes, then 170°C (fan 150), gas 3 | Loosely with foil after the first 30 minutes | About 4¼ hours in all |
| Co-op | 1.8kg | 160°C (fan 140), gas 3 | Foil, off for the last 15 minutes | 4 to 5 hours |
| Budgens | 2kg | 180°C (fan 160), gas 4 | No | 4 hours |
| Good to Know, seven-hour leg | About 2.4kg, bone in | 120°C | Lid on (or tray with two layers of foil) | 7 hours |
| Super Golden Bakes | 2.2kg, bone in | 160°C (fan 140) | Covered, then uncovered | 3½ hours covered plus 30 minutes |
| The Ginger Pig (butcher), boneless leg | About 2kg | As hot as it goes, then 140°C | Not stated | 3½ hours, lifted at 60°C for medium |
The Good to Know seven-hour recipe states 120°C only, with no fan figure, so check your oven’s guidance.
Choosing your joint
Bone-in or boneless
Bone-in is what most slow-roast recipes use. A leg of about 2kg is common, and the recipes serve between 4 (Co-op, 1.8kg) and 8 (Sainsbury’s Magazine, 2 to 2.25kg), because bone weight and the amount of sides differ. Boneless is smaller and shorter, and we found one UK butcher’s schedule for it (the Ginger Pig above). We found no tested slow-roast timing for a boneless leg, so start the fork test earlier.
Half leg or whole leg
For a slow cooker, the Flawless Food blog notes that a half leg runs 600g to 1.2kg and a whole leg 1.3kg to 3kg, and a half leg fits most pots.
Prepping and seasoning
The Sainsbury’s Magazine method makes a paste of garlic, salt, chopped thyme and oil, stabs the lamb all over, cuts a few deeper slashes and massages the paste in. It also says you can prepare it the night before and chill it, then bring it back to room temperature for at least 30 minutes before cooking.
Best herbs for roasting lamb leg
The best herbs for roasting lamb leg are a matter of taste, but the recipes we read agree on a short list. Sainsbury’s uses thyme, the Good to Know seven-hour recipe uses sage and bay, the Co-op recipe uses oregano with cinnamon and lemon, and Jamie Oliver’s rosemary and garlic shoulder uses rosemary. Schwartz, which sells herbs, calls rosemary the best fit for roast lamb and mint better as a sauce. That is a brand’s view.
Roasting lamb leg covered or uncovered
Do you cover a leg of lamb when slow roasting? Most recipes do. Sainsbury’s loosely covers the tin with foil, the Co-op uses foil, and the seven-hour recipe uses a tight lid. RecipeTin Eats says to use foil and not a lid, because you want a little liquid to steam out. The How Food Works newsletter, by Fiona Fitwi, recommends tightly covering with two layers of foil, and adds liquid to help the heat travel evenly and make a broth for gravy. That is one writer’s explanation, not a test.
The exception is Budgens, which roasts the leg uncovered at 180°C (fan 160) for 4 hours. Every other recipe covers it for most of the time, then uncovers it for 15 to 40 minutes at the start or the end to brown. That is the pattern we would follow.
Low and slow timings
A starting method (built from the sources, not tested)
This method for a bone-in leg of about 2kg combines the Sainsbury’s Magazine and Co-op recipes:
- Take the lamb out of the fridge 30 minutes before cooking and rub on your paste.
- Roast it uncovered at 200°C (fan 180), gas 6, for 30 minutes.
- Reduce to 170°C (fan 150), gas 3. Pour 150ml white wine and 150ml water around the lamb, not over it, and cover the tin loosely with foil.
- Roast for 2 hours, then check the liquid and top up if it has dried out. Sainsbury’s adds onions and fennel at this point and cooks for a further 1 to 1½ hours.
- Test with a fork from about 3 hours. If the meat does not pull away from the bone, put the foil back and give it more time. Co-op runs to 4 to 5 hours at a lower 140°C (fan).
- Take the foil off for the last 15 to 30 minutes if it needs colour.
- Rest, then make the gravy.
Internal temperature for slow roast lamb
Internal temperature for slow roast lamb depends on the finish you want. For a carvable, pink joint, the Ginger Pig lifts a boneless leg at 50°C for rare or 60°C for medium. For fall-apart lamb, the How Food Works newsletter gives about 95°C at the centre, and says collagen turns slowly into gelatin at low heat, giving tender meat. We found only that one source for 95°C, and RecipeTin Eats says you do not need a thermometer, only that the meat is tender enough to pry a bit off with a fork.
On safety, safefood says whole lamb joints can be eaten pink because bacteria are on the outside, but advises that people who are elderly, pregnant, very young or unwell avoid pink lamb. A slow-roasted joint is cooked far beyond that point.
Tender fall off the bone lamb: what makes it happen
Tender fall off the bone lamb is a matter of time more than heat. Collagen, the connective tissue, needs hours at a low temperature to break down. Overshoot and the meat dries. A slow cooker reviewer on Flawless Food cooked a half leg for 8 hours instead of 7 and found it dry and tough, which is a reminder to adjust for the size of the joint.
Slow roast leg of lamb for 7 hours, or overnight
Slow roast leg of lamb 7 hours
The seven-hour recipe from Good to Know cooks a bone-in leg of about 2.4kg at 120°C for 7 hours with the lid on, turning the leg halfway through. The pot has half a bottle of dry white wine, 500ml of water and a tablespoon of runny honey, with garlic, bay and sage. That is the low-temperature end of the sources we found.
Slow roast leg of lamb overnight
Slow roast leg of lamb overnight can mean two things. The first is preparing overnight: Sainsbury’s Magazine says to prepare the lamb to the end of the paste stage the night before and chill it. The second is cooking overnight, and there the sources are thin. The How Food Works newsletter suggests staying within 95 to 110°C for a low-risk result, and the What Katie Ate recipe cooks a 1.2 to 1.5kg leg for about 9 hours 20 minutes at 140°C, after an overnight marinade. We found no UK food safety guidance on leaving an oven on unattended overnight, so check your oven’s manual and be cautious.
Overnight slow roast lamb recipe: a safer plan
Our suggestion, not a tested one: marinate overnight, then cook it the next morning on a 4 to 5 hour schedule. It gives most of the benefit with none of the overnight worry.
Other ways to cook it
Slow cooker leg of lamb bone in
Slow cooker leg of lamb bone in is possible if the joint fits. The Flawless Food blog gives low for 7 hours for a half leg and 8 hours for a whole leg, with a stock pot dissolved in 300ml boiling water poured around the joint and the lid kept on throughout. It has not tested the high setting. For crisper skin it suggests 20 minutes in a hot oven at the end.
Braised leg of lamb red wine
For braised leg of lamb red wine, Good to Know’s recipe uses a 1.8kg leg with 600ml of red wine at 180°C: seal the tin with foil for 2½ hours, then uncover for 20 minutes. It finishes the sauce by reducing the tin liquid with redcurrant jelly. Super Golden Bakes uses 250ml of red wine and 500ml of hot chicken stock at 160°C (fan 140) for 3½ hours covered and 30 minutes uncovered.
Slow roast leg of lamb recipes people search for
Slow roast leg of lamb Jamie Oliver
For slow roast leg of lamb Jamie Oliver searches, we did not find a leg recipe on his own site that we could open. His slow recipes we found are for shoulder. His rosemary and garlic lamb shoulder (2kg) goes in at 200°C for 20 minutes, then 160°C under double foil for 4 hours or until the meat pulls easily from the bone. His tender lamb shoulder in 5 Ingredients goes into a cold oven at 170°C for 6 hours, covered, with chickpeas. Several other sites claim Jamie Oliver leg recipes, and we did not use those.
Slow roast leg of lamb recipe BBC Good Food
We could not open a BBC Good Food page for a slow roast leg of lamb recipe, so we do not report what it says. Check it directly.
Slow roast leg of lamb Maxwell Colonna
Readers also search for slow roast leg of lamb Maxwell Colonna. We could not find a recipe under that name, so we have not attributed anything to it.
Resting and carving
How long to rest
Rest the lamb loosely covered with foil. The Co-op and RecipeTin Eats say 15 minutes, while Flawless Food and the How Food Works newsletter say at least 30 minutes, and the Ginger Pig says up to an hour for a roast joint. A slow-roasted leg stays warm for a good while. RecipeTin Eats says one to one and a half hours.
How to carve leg of lamb
How to carve leg of lamb, according to Waitrose:
- Holding the bone, turn the leg so the thickest, meatiest part is uppermost.
- Cut a narrow wedge of meat from the centre of the joint.
- Carve slices down to the bone, with the knife angled along the line of the wedge, then cut across the base of the slices to free them from the bone.
- Turn the joint over and carve the remaining meat parallel to the bone.
A fall-apart leg will not hold slices. Jamie Oliver’s slow shoulder is pulled apart with two forks, and the same works here.
Gravy from the tin
The tin liquid is the base of the gravy. The recipes agree on the steps and differ on the thickener:
- Lift the lamb out to rest. Spoon or pour off the fat, keeping the dark juices.
- Put the tin on the hob, or pour the juices into a pan.
- Thicken. Jamie Oliver’s shoulder stirs in 1 tablespoon of plain flour, cooks it for 2 minutes, then adds 500ml of boiling water and some wine and simmers for 15 minutes. RecipeTin Eats adds 4 tablespoons of flour to the simmering pan juices from a larger tin and whisks in water. Flawless Food strains the liquid and whisks in 2 tablespoons of cornflour mixed with cold water.
- Simmer for 10 to 15 minutes, strain, taste and season.
The amounts vary a lot, so start with the smaller one and add more only if needed. If it goes lumpy, see our guide to thickening a curry or stew without making it lumpy. For a quicker cut, there is also our guide to cooking lamb steaks so they stay pink and tender.
Frequently Asked Questions
How long do you slow-roast a leg of lamb until it falls apart?
For a 2kg bone-in leg, about 4 to 5 hours at 140 to 160°C fan, covered, is typical in UK recipes. Test with a fork from about 3 hours. At 120°C one recipe takes 7 hours. The meat is ready when it pulls from the bone.
What is the slow roast leg of lamb temperature and time?
Between 140 and 160°C fan for 4 to 5 hours is typical, or 120°C for 7 hours. Some start with 20 to 30 minutes at 200°C to brown it. Joint size and oven vary, so go by tenderness, not the clock.
Do you cover a leg of lamb when slow roasting?
Usually yes. Most recipes use foil or a lid and a little wine, stock or water in the tin, then uncover for 15 to 40 minutes to brown. Budgens roasts a 2kg leg uncovered at 180°C for 4 hours instead, so it can be done.
Is a slow roast leg of lamb for 7 hours too long?
Not at 120°C. The Good to Know recipe cooks a bone-in leg of about 2.4kg for 7 hours with the lid on. At 160°C a leg would be dry well before that. In a slow cooker, one reviewer found an extra hour made a half leg tough.
Can you slow roast leg of lamb overnight?
You can prepare it overnight: season it and chill it, as Sainsbury’s Magazine suggests. Cooking in the oven overnight is less well covered, and we found no UK safety guidance on it. We suggest marinating overnight and cooking the next day.
How do you get slow cooked leg of lamb that falls off the bone?
Time at a low temperature. Collagen turns slowly into gelatin, so the meat loosens. One newsletter gives about 95°C at the centre, and RecipeTin Eats uses a fork test. Too long or too hot dries it out.
