For the apple and cinnamon chutney, soak the sultanas in a bowl with 100ml/3½fl oz of water for 10 minutes.
Heat the butter in a pan over a low heat, add the shallots and cook until softened, but not browned. Add the apple and allow to cook for a few minutes.
Add the sultanas and their soaking water, the brown sugar and cider vinegar. Cover and simmer gently for 15 minutes, stirring until the sugar has dissolved.
Stir in the cinnamon, balsamic vinegar, star anise, thyme, salt and pepper. Simmer until the volume of liquid has reduced and has thickened to a chutney consistency. Set aside.
To make the sausage rolls, heat the sunflower oil in a small pan, then add the onion and celery and cook gently until soft, but not browned. Stir in the garlic and thyme and cook for 5 minutes longer.
Pour in the port and simmer until it has completely evaporated. Remove from the heat and leave to cool.
Put the prunes into a separate pan, add the brandy and 2 tablespoons of water, and simmer until all the liquid has evaporated. Set the prunes aside to cool.
Put the cranberries into the pan, add enough cold water just to cover, and simmer until the cranberries are tender. Drain well and allow the cranberries to cool slightly. Transfer the prunes and cranberries to a chopping board and chop roughly.
Put the sausage meat into a bowl, add the onion and celery mixture, prunes, cranberries, spices, salt and sage and mix well. (Check the seasoning by frying a small amount of the mixture until cooked through. Taste and adjust as necessary.)
Take a disposable piping bag and snip off the end; you need the opening to be roughly 2.5cm/1in in diameter.
Unroll the pastry sheet onto a lightly floured work surface and roll it out just a little across its width, so it is 1cm/½in wider. Cut it lengthways in half.
Pipe half of the sausage mixture down the centre of one piece of pastry. Brush down one side with beaten egg, then fold the pastry over the sausage meat and press the edges together to seal. You should have a flat lip on one side, where the edges join. Repeat with the other piece of pastry. Reserve the beaten egg.
Press down all along the lip with a fork to mark it. Cut into four sausage rolls and place them on a baking tray lined with baking parchment. Repeat with the remaining pastry and filling. Chill in the fridge for 15 minutes.
Preheat the oven to 180C/160C Fan/Gas 4.
Brush the sausage rolls with more beaten egg and bake for 20–25 minutes, or until the sausage rolls are golden brown and cooked right through. A good way to make sure they are cooked is to check the underneath; the pastry should be lightly golden.
Serve the sausage rolls with the chutney on the side.