My grandmother has an old, blackened clockwork spit-turner we use by an open fire every time we are at her apartment in Sperlonga. It is most effective, making a little tinkling sound when it runs out of oomph, the spit starting to turn more slowly and threatening to burn the meat. It has just enough strength to turn a leg of lamb.

A leg serves 5–8

1 leg of lamb on the bone 4 sprigs rosemary
4 garlic cloves, peeled and halved
100g aromatic honey – chestnut or wild thyme
1 tablespoon white wine
Pick the leaves from half the rosemary. Make eight incisions in the lamb with the tip of a knife and stuff each with a bit of garlic and a few rosemary leaves. Rub the lamb with plenty of salt and pepper, and about a quarter of the honey. Thin the rest of the honey with the wine, to baste the meat with later. To cook like my grandmother (and this works only with a leg), force a sturdy spit of decent weight through the lamb, running lengthways parallel to the bone, and making sure the weight is evenly distributed for the spit to turn. Secure the lamb with a couple of metal spikes that screw on to the spit. Roast the lamb next to an open fruitwood fire, about 20cm from the flames. Adjust the distance according to the ferocity of the fire so the lamb browns deeply without burning as it cooks. Baste the lamb with the thinned honey, using the remaining rosemary sprigs as a paintbrush, and catch the drippings with a metal tray. To cook in an oven, roast in a tray for 30 minutes at 200˚C/Gas 6 until browned. It would be a shame not to roast a few potatoes around the lamb, which should go in at the same time. Turn the oven down to 180˚C/Gas 4 (leg), and baste the meat regularly with the winey honey until done.In my opinion, legs (of lamb at least) are better judged by the senses than by time.* Whether cooked over a wood fire or in a domestic oven, to check a leg for doneness insert a metal skewer or thin blade into the thickest part of the meat, and test its temperature by putting its tip against your lower lip: cool = undercooked; tepid = rare; just warm = medium-rare; quite warm = medium; uncomfortable = medium-well done; painful = well done. Leave the lamb to rest for 15 minutes covered loosely with foil before serving.
*Timings are necessarily inaccurate: lamb legs of the same weight vary in shape, they start from differing ambient temperatures, fires burn up and burn down, and ovens are as different as the people who use them. That said, for indicative purposes only, a spit-roast leg by an open fire will take about 1½ hours for a 2kg leg, plus 30 minutes for each additional 500g. In an oven, after the initial 30 minutes at 200˚C/Gas 6, allow 40 minutes at 160˚C/Gas 3 for a 2kg leg, plus an extra 20 minutes per additional 500g. But even in a reliable oven I never time my roasts…