Cut the beef into 4cm chunks and toss with plenty of seasoning. Heat 2 tablespoons of the oil in the casserole dish over a high heat, add the bacon, and fry briskly until golden. Remove with a slotted spoon to a plate. Add 4-5 pieces of the beef and lower the heat slightly. Brown them well over a medium-high heat, spoon onto a plate and repeat with the rest of the beef.

Add the rest of the oil to the pan with the onions and sugar and fry them for about 10 minutes, stirring frequently, until they are richly caramelised. Add the garlic and cook for 1 minute.

Stir the flour into the onions, followed by the brown ale, stock, thyme leaves, bay leaves and Worcestershire sauce and bring to the boil, stirring. Return the beef and bacon to the pan and season with a little more salt and pepper. Part-cover and simmer for 1½ hours, stirring gently occasionally.

Halve, quarter or leave the mushrooms whole, according to their size. Melt the butter in a small frying pan, add the mushrooms and fry briskly for 2 minutes. Stir them into the beef and continue to cook for another 30 minutes until the beef is tender and the sauce has reduced and thickened nicely. Remove and discard the bay leaves, push a pie bird or funnel into the middle of the mixture and leave it to go cold.

Roll out the puff pastry on a lightly floured work surface and using the lid of the casserole as a template, cut out a pastry oval that is 2cm larger than the top of the lid all the way around. Cut a small cross in the centre.

Brush the rim and outside edge of the casserole dish with a little beaten egg. Lay over the pastry lid so that the pie bird or funnel pokes through the hole and press it firmly onto the edge and down the sides of the casserole dish to ensure it is sealed. Decorate around the pie bird/funnel with some pastry leaves cut from the trimmings and mark the edge of the casserole with the tines of a fork. Chill for 30 minutes.

Preheat the oven to 200°C / 400°F / Gas Mark 6. Bake the pie for 30-35 minutes until the pastry is puffed up, crisp and golden and the filling is bubbling hot.

Cook's Notes:

For a deeper mushroom flavour, fry 25g pre- soaked porcini mushrooms after the onions have softened.