Take your sausage string and unwind the joins. Push the sausage meat to one end so you are left with one very long sausage. Wind into a spiral and secure with a skewer. Bake for 20 minutes until golden.
While your sausage spiral is cooking, make the onion gravy.
Melt the butter in a frying pan and add the onions and sugar. Cook until very soft then add the flour. Stir, cook out for one minute then add half the stock. Stir to avoid lumps then add the rest of the stock and bring to the boil.
Once boiling, add the seasoning Worcestershire sauce and sage. Stir again and allow to thicken slightly, then set aside.
By now your sausages will be nicely caramelised. Remove the skewer and place the sausages in a pie dish. Pour over the gravy and place the pastry lid on top.
Press the pastry down and crimp the edges. Brush with beaten egg, make a hole in the centre for steam to escape and bake for 20-30 minutes. Serve immediately.