Dip the meat into the seasoned flour, then place a large lidded pan on the hob.
Heat half the butter in the pan and add the meat. Sear all over until golden brown.
Add the vegetables and herbs, then pour in the ale and stock. Bring to a simmer, then cover with a lid and gently simmer on the stove for 1½ hours.
Preheat the oven to 220C/425F/Gas 7.
Once cooked, season the stew, add the remaining butter and tip into an ovenproof serving dish. Brush the edge of the dish with the beaten egg.
If necessary, roll out the pastry using as little flour as possible and place over the dish. Pinch the edges of the dish so that the pastry will stick to it and trim off any remaining pieces of pastry from around the edge. Cut the leftover pastry into leaves and add them to the top, using the beaten egg as a 'glue', for decoration.
Brush the pastry top thoroughly with the remaining beaten egg and place on a baking tray. Bake in the oven for 20-30 minutes until the pastry is golden brown on top. Serve.