Preheat the oven to Gas mark 4-5, 180-190°C, 350-375°F.
To prepare the garlic and herb butter; in a small bowl mix all theingredients together. Place the joint on a chopping board, score the skin,season and spread generously all over. Wrap any remaining butter in cling filmor foil and freeze for up to 2 months.
Place the joint on a rack in a roasting tin and open roast for thepreferred, calculated cooking time, basting occasionally with any rich meatjuices. Cover with foil if browning too quickly.
Remove from the oven; cover and leave to rest on a large plate for 15-20 minutes. Meanwhile, make the gravy; spoon off any excess fat from theroasting tin and discard. Place the roasting tin over a medium heat andsprinkle over the flour. Stir well with a small whisk or spoon, add a little stock and stir again, scraping the base of the pan to release any richsediment.
Add the remaining stock, cider and any meat juices from the plate.Adjust the seasoning if required and simmer for 8-10 minutes, stirringoccasionally until reduced to a well-flavoured gravy. Strain before serving.
Serve the lamb with seasonal vegetables and the gravy.