Heat 1 tbsp oil in a frying pan and fry the onion, garlic, ginger and chilli for 5 minutes. Stir in the rest of the curry powder, allspice, cloves, thyme and cinnamon and cook for a minute. Add the lamb and fry for 5 minutes. Add the tomatoes and sugar. Refill the tomato tin with water and stir this in. Add a chicken stock cube. Bring to a simmer, cover and cook for 1 hour. Remove the lid and simmer for a further 30 minutes, stirring regularly towards the end. Serve with steamed rice and lime wedges.