I first tried a similar recipe to this from Stephanie Alexander's book: Cooking and Travelling in South West France. For those reading who are not Australian, she is as close to we get as a mother and mentor to all food lovers. She doesn't only cook - she also used to run one of the most famous restaurants in Melbourne, and now she has "retired" to the garden - A kitchen garden, for kids. She's a bit of a superwoman really...
Anyway.
I made her 7-hour lamb with anchovies and garlic, and it was incredible. When I tried to lift the leg out of the pot, the entire bone came away. Our neighbours had been smelling at our door all day, and literally came begging - for food, and the recipe.
I've made it several times since. I still call it seven hour lamb, but sometimes its 7 hours at 120°C, and others its 5 hours at 140°C. Sometimes I make it with a bone-in leg of lamb, and sometimes I make it without the bone. Sometimes it fits in a pot, and others, when it doesn't (like last night), I put it in a deep tray and cover it with a few layers of foil. It always works. It's a fairly traditional french recipe, and it appears many chefs make a version (including Nigella). My simplified one is below.