Preheat the oven to 180C/350F/Gas 4.
Season the lamb with salt and pepper and set aside for 10 minutes.
Heat an ovenproof frying pan, add the olive oil and the rumps of lamb and brown them all over. Add the rosemary and garlic and transfer the pan to the oven and roast for 5-6 minutes, or until cooked to your liking.
Once cooked, remove the lamb from the pan and set aside to rest. Keep warm until ready to serve.
Using the same pan, return it to the heat, adding a little more oil if needed. Cook the bacon lardons for 1-2 minutes so the lardons start to colour, then add the carrots and cook for a further 2-3 minutes. Add the peas and season to taste with salt and pepper, before covering with the chicken stock. Cook on a high heat for 3-4 minutes, adding more stock if needed.
Once the peas are cooked, add the wild garlic, lettuce and mix in a knob of butter.
Serve the lettuce, bacon and peas in bowls with the slices of lamb rump on top.