Heat oven to the highest setting
Using a sharp knife make a series of slashes on the meat
In a deep roasting tray lay half the rosemary and half the garlic cloves
Sit the lamb on top
Pour a little olive oil on the lamb
Season with salt and pepper and rub it in
Put the remaining rosemary and garlic on top
Cover the tin with aluminium foil and seal it well
Put it into the oven
Now turn the oven DOWN to 170C
Leave to cook for at least 4 hours
Remove from the oven , put on a plate and cover with foil . Leave for at least 15 minutes before serving
The meat will pull apart
Use the pan juices to make your gravy , squeezing the roasted garlic from the cloves