• Heat oil in a large pan and add the onion, carrot and celery. Cook over a medium heat until soft - approximately 5 minutes.
• Add the garlic, thyme and rosemary to the pan. Cook for a further 2 minutes.
• Add the beef to the pan and cook over a medium-high heat until well browned.
• Add the flour and tomato paste and stir to combine.
• Slowly add in the stock, stirring all the time.
• Add in the wine and Worcestershire sauce and mix well.
• Add bay leaves and season well with salt and pepper.
• Bring to the boil and allow to bubble away for at least 30 minutes to allow the flavors to infuse and the sauce to thicken.
• Meanwhile cook the mashed potatoes (see below) and pre-heat the oven to 360F / 180C.
• Once the potatoes are ready and the sauce is nice and thick, add the peas to the pan and stir.
• Transfer the meat sauce to an ovenproof dish. Top with the mashed potato and smooth down. Use a fork to make a pattern on top of the mashed potato then sprinkle with the cheese.
• Bake in the oven for 25-30 minutes until the pie is browning on top.

To make the mashed potato

• Peel and cut the potatoes into even sized pieces.
• Put potatoes into a large pot, cover with cold water and add the salt.
• Bring to the boil, reduce heat to medium-low and allow to bubble gently for around 15-20 minutes until the potatoes are very tender but not falling apart.
• Drain the potatoes and return to the pan and allow the potatoes to dry a little over a low heat for a minute or two.
• Mash with a potato masher until no lumps remain.
• Then add the butter and continue mashing, gradually adding the milk until you have a nice creamy consistency. Season with salt and pepper.