Make an incision in the skin between the legs and the body. Hold the turkey up by one leg and slice around the joint between the thigh and the body to take off the whole leg in one piece. Repeat with the other leg.

Debone each leg. Lay it skin side down and feel for where the two long bones run. Slice along them until you hit bone, then work around both sides until they are mostly exposed.

Pierce the knife under the drumstick bone and slice towards where the foot was. Lift the leg by the exposed bone and slice down it to free it from the meat. Repeat with the thigh bone, slicing out towards where the body was, then lift the leg by the free end and slice down until the meat is completely off the bone.

Feel for bone fragments and cartilage. Slice out the cartilage around the knee joint without cutting through the skin on the other side, and slice out the thin, toothpick-like bones in the drumstick. Repeat with the other leg.

Lay five 50 cm / 20 inch lengths of oven-safe string evenly spaced on a chopping board. Place one leg on the strings with the widest part of the meat at the top. Slice out the highest point of the meat and place it in the empty patch where the knee cartilage was.

Lay the stuffing in a cylinder down the middle of the leg. Slice the high point out of the second leg in the same way, then lay that leg on top, skin side up, with its widest part at the opposite end to the first leg. Shape the meat into an even cylinder.

Tie the second piece of string with a left over right knot, looped one extra time and pulled tight, then add another left over right knot to lock it. Tie the fourth, third, first and fifth strings in that order, which keeps the shape even. Trim off the excess string.

Make the crown. Hold the bird up by one wing and, halfway between the first wing joint and the joint on the body, slice through and run the knife 360 degrees around the bone. Bend the wing back until the joint dislocates and comes free. Repeat with the other wing.

Turn the body 90 degrees and slice off the rear section: find the gap in the spine and push the knife through. What is left is the crown. Keep the bones to make a stock for gravy.

Optional: remove the wishbone to make carving easier. Feel for the bone on either side of the neck opening, pierce the knife in behind it and out the other side, and cut firmly down through it. Do the same on the other side, slice up towards where the two bones meet, then grip the bone and twist it free.

From the neck end, gently work your fingers between the skin and the meat to free it. This lets air in for crisper, golden skin. Go slowly so you do not tear the skin. Trim off any excess skin at the neck end, leaving a little extra for shrinkage.

Lift the skin from the neck end, sprinkle in a few pinches of the salt and gently rub it into the meat. Flip the crown upside down and season the underside a little, then season the outside of the skin.

Season the outside of the stuffed leg all the way around with the rest of the salt. Use less on the leg than on the crown, because the stuffing is already seasoned.

Refrigerate the crown and the stuffed leg, covered, for 24 to 72 hours.

Work backwards from your eating time using the cooking times table in the post: subtract the rest time, the cook time and 60 minutes for the turkey to come out of the fridge. For a 2.5 kg / 5.5 lb crown to be on the table at 3 pm, take it out of the fridge at 11 am.

Heat a large frying pan over a medium heat for 2 minutes. Add a splash of cooking oil and brown the stuffed leg, turning it regularly, until it is evenly golden all the way around. This took about 15 minutes.

Preheat the oven to 180°C / 355°F fan assisted, or 200°C / 390°F with no fan.

Put the sliced onions, carrots, celery, rosemary and thyme in the roasting tray to make a trivet. Place the crown and the stuffed leg on top. Optionally, slide slices of butter under the skin of the crown. Start the crown with the cavity facing down. Once the turkey has been out of the fridge for 60 minutes, put the tray in the oven.

Roast for the time in the table, which is 2 hours for a 2.5 kg crown. Baste the meat with a serving spoon three times, at 30-minute intervals. At the first baste, turn the crown up so it sits on the wing joints.

At the third baste, around three quarters of the way through, check the stuffed leg and the crown with a meat thermometer to see how much longer they need. Stab the meat only once and use the same hole each time, because juices run out of any holes you make. At this stage the leg was 71.4°C / 160°F and the crown 70°C / 158°F, and I wanted both a little higher.

The crown is ready at 74°C / 165°F and will rise to around 80°C / 176°F as it rests. The leg meat is more forgiving because of its intramuscular fat, so anything above 76°C / 168°F is good.

Rest the turkey, covered in foil, for at least half the cooking time and up to the whole cooking time. The rest time for your crown is in the table. The meat holds its heat for a very long time under the foil, and the rest gives you time to get everything else to the table.