Heat the olive oil in a large saucepan over a medium heat. Add the mince and the onion and fry for five minutes, stirring occasionally, until the mince is browned and the onions softened.
Add mushrooms and carrot, cook for around one minute, then add tinned tomatoes, vegetable stock, tomato purée, Worcestershire sauce and freshly ground black pepper. Stir well and bring to the boil, then reduce the heat to simmer for 15-20 minutes, until the sauce has thickened.
Place the wholemeal spaghetti in a deep saucepan full of salted boiling water and cook according to packet instructions, then drain.
To serve, divide the cooked spaghetti between four dishes, spoon equal portions of Bolognese sauce over each and sprinkle with parsley.