Place the lamb flat in the roasting tin, skin side down. Mix the herbs and garlic together. Spread the mixture over the lamb along with a squeeze of lemon juice, a drizzle of olive oil and sprinkling of black pepper. If possible allow the lamb to marinate for about an hour before cooking. Sprinkle some salt over the lamb just before cooking.
Set the oven to Gas Mark 7, 220°C (450°F). Roast uncovered for approximately 45 minutes to serve pink.
Coat the potatoes in a tablesp. of the oil and season well. Cook them in the oven with the lamb for the last 20 minutes until crispy and tender. Blanch the green beans for a minute or two. Drain and mix in a large bowl with the tomatoes, garlic, remaining oil and season with a little salt and pepper. Add the lot to the potatoes and continue to roast until the tomatoes are just soft, for about 5 minutes. Sprinkle with basil. Mound warm vegetables in a shallow bowl and drizzle with lemon juice and server with the sliced lamb.