To make the stuffing, heat the oil and gently fry the onion and leek for 5 minutes, or until well softened and lightly browned, stirring regularly. Tip into a mixing bowl and leave to cool for 30 minutes.
For the turkey, generously oil a small, sturdy roasting tin, roughly 30cm x 22cm/12 x 8½in – the turkey needs to fit snugly.
To continue the stuffing, once the onion and leek are cool, add the cranberries, almonds, lemon zest, thyme and breadcrumbs. Squeeze the sausage meat out of the skins and add it to the bowl.
Season with salt and lots of pepper. Mix well with a spoon or with clean hands until thoroughly combined.
Place the turkey breast on a board and gently remove the skin. Turn over and cut horizontally almost all the way through the thickest part of the breast and open up like a book, so that the turkey has a flatter, more oblong shape. Cover with a sheet of cling film and bash with a rolling pin until around 2.5cm/1in thick all over.
Place a sheet of cling film on a work surface and put eight pieces of kitchen string, each 50cm/20in long, roughly 4cm/1½in apart along its length. Stretch each rasher of bacon with the back of a knife until around 32cm/13in long. Place the bacon rashers on top of the string and cling film, overlapping each slice.
Place the turkey breast, smooth-side down, on top of the bacon and arrange the filling all the way down its length. Bring up the cling film and bacon on both long sides to enclose the filling.
Tie firmly with the string and discard the cling film. Place the turkey parcel in the prepared tin, knot-side down. (You can cover and chill for up to 24 hours before cooking if using a fresh turkey joint, or cook the same day if using a previously frozen joint.)
Preheat the oven to 200C/180C Fan/Gas 6. Uncover the stuffed turkey joint, then drizzle with oil and season with black pepper. Cover loosely with foil and roast for 1 hour. Remove the foil and continue cooking for a further 30–45 minutes, or until the bacon is crisp and the turkey and stuffing are thoroughly cooked.
Transfer the turkey to a warmed platter. Cover with foil and a tea towel and leave to rest for 15 minutes.
For the gravy, put the roasting tin on the hob over medium heat and stir in the flour. Add the wine and cook for 15–20 seconds, stirring constantly.
Gradually add the stock, stirring all the time. Bring the liquid to a simmer, stir in the redcurrant jelly and cook for 2 minutes, or until thickened and glossy. Season to taste, strain carefully (the tin will be extremely hot) through a sieve into a saucepan and keep warm until ready to serve.
Snip the string off the turkey and garnish with bay leaves and thyme. Carve into slices and serve with the hot gravy.