Preheat oven to 230°C/Gas Mark 8.
Remove turkey giblets and reserve. Rinse the turkey inside and out and dry well.
To prepare the stuffing, cut the crusts off the loaf of bread. Then tear the loaf into 2cm pieces. Place the croutons in a bowl and toss in 6 tbsp of rapeseed oil. Use your hands to do this and squeezing the bread into the oil and season well with sea salt and freshly ground black pepper. Place on a baking sheet and cook in the oven for 10-15 minutes, tossing often, until the croutons are golden brown and crispy on the outside, but still a little soft. Place the cooked croutons on the side to cool.
Heat a large frying pan, add the remaining rape seed oil and the butter and cook the bacon and onion for 2-3 minutes, stirring all the time, until the bacon and onions are just golden, then add the chestnuts and cook for a further 2 minutes on a low heat Remove from the heat and place in a large bowl, add the cherries, thyme, rosemary, garlic and parsley, zest and juice of lemons and the beaten egg, then mix well. Add the croutons and stock and combine the mixture together. The stuffing will be quite loose. Season well with sea salt and black pepper. Place the stuffing into an oven proof dish and set aside until ready to bake.
Place two tablespoons of the stuffing into the small cavity (neck end) of the turkey, pull excess skin over stuffing and secure to underside of turkey with a wooden skewer. Place the turkey in a large roasting pan. Brush the turkey generously with rapeseed oil and season with sea salt and black pepper and cover with foil.
Place the prepared turkey in the pre-heated oven and cook at this temperature for the first 30 minutes. Then, lower the oven temperature to 180°C/Gas Mark 4 and cook for approximately 30 minutes per kilo, basting every hour.
Meanwhile cover the stuffing with foil and bake for 45-50 minutes, removing the foil 10 minutes before the end of cooking, until the top has a slightly crispy top.
When the turkey is approximately 35 minutes before the end of cooking, remove the foil, drain off any of the excess fat and cook for a further 35 minutes or until golden brown.
Transfer the turkey to a platter and cover loosely with foil and leave to rest for 20-30 minutes.
Serve the turkey carved with slices of stuffing and warm homemade turkey gravy with sherry.
To make the turkey gravy with sherry, wash the giblets in cold water, place in a large pan with 1.5 litres of cold water. Bring to the boil and removed any scum of the top of the water with a slatted spoon. Then add the rest of the ingredients, cover and simmer for 40minutes.
Uncover the pan and simmer for a further 20-30 minutes or until the stock has reduced by half. Remove from the heat and strain into a bowl, leave to cool, cover and place in the fridge or use immediately.
To make the gravy, bring the stock back to the boil and remove from the heat.
When the turkey is cooked pour off the fat from the roasting juices, place the tin on the hob, whisk in the flour and place over a low heat and cook the flour mixture making sure you have scrapped up all the meaty sticky bits, on the bottom of the tin and stir constantly. After 2 minutes, remove from the heat and whisk in the turkey giblet stock, bring slowly to the boil, stirring constantly.
Add the sherry and cook for a further 3 minutes, stirring constantly. Season to taste add a little more sherry if you want and then strain into a warm jug and serve. Any leftover turkey sherry gravy can be frozen.
The giblet stock can be made 2 days before required.