Season the butterflied lamb all over with Maldon salt. Combine the marinade ingredients and marinade the lamb for 24 hours, turning it halfway through the time.
Once it’s been marinated, remove the lamb from the marinade and air dry in the fridge on a cooling rack, uncovered for a further 24 hours, reserving the marinade for the stock.
Have the wood fired oven at around 450°C with a small flame presence and pop the bones and lamb trimmings into a tray with the olive oil and roast for 15-20 minutes or until starting to caramelise.
Add the garlic, celery and carrots and cook for a further 10-15 minutes. Add the onions, bay and thyme and roast for a final 20-25 minutes.
Transfer the contents of the tray to a tall stock pan along with the tomatoes and reserved red wine and reduce the wine by half. Top up with cold water and the stock cube, bring to the boil before reducing the heat to a steady simmer for 45-60 minutes. Pass through a fine sieve and set aside.
Rub both sides of the lamb with a little olive oil and season well. Place the lamb skin side down on a double sheet of foil before carefully placing in the centre of the oven, directly on the floor.
Cook for 7-8 minutes before turning the lamb over and cooking for a further 5-6 minutes. Allow to rest for 15 minutes before carving and serving with the reduced sauce.