1. Preheat the oven to 180°C, gas mark 4 and cook the haggis according to pack instructions.
2. Meanwhile, make the gravy. Heat the oil in a large pan and fry the vegetables for 5 minutes until just brown. Add the flour and tomato purée and cook for 2-3 minutes. Slowly add the stock, stirring until smooth. Bring to the boil and simmer gently for 30 minutes, then pass through a sieve. Return the gravy to a clean pan and add the redcurrant jelly, Worcestershire and Tabasco sauces. Simmer for 5 minutes, then remove from the hob and reheat before serving, if necessary.
3. Place the potatoes (tatties) in a pan and cover with cold water. Bring to the boil and simmer for 12-15 minutes until tender. Drain, and allow to dry in the pan for 2-3 minutes, then mash. Warm the milk and half the butter in a pan until the butter has melted. Stir into the potato and season.
4. Place the swede (neeps) in a pan and cover with cold water. Bring to the boil and simmer for 15 minutes until tender. Drain and return to the pan to dry out for 2-3 minutes. Mash, stir in the remaining butter and season.
5. Reheat the gravy, neeps and tatties if necessary. Remove the haggis from the oven. Make a slit through the casing and pour in the whisky. Serve spoonfuls of haggis with the tatties, neeps and gravy.