Preheat oven to 350F.

Peel and chop the onion, carrot, celery and potato into 1cm sized dice.

Place all vegetables and rosemary leaves into a frying pan with olive oil. Fry and stir for about 8 mins or until vegetables soften and colour.

Add frozen peas and cook for another minute.

Put vegetables into large bowl to cool completely.

Add the minced beef to the bowl with salt and pepper and half the egg. Scrunch together.

Roll out pastry to size of small tea towel.

Place mince mix along one long side, in sausage shape.

Brush edges of pastry with egg and roll pastry to cover mince completely. Squeeze ends together.

Put onto baking tray, brush with egg. Bake for 1 hour until golden.

Slice and serve with gravy.