Preheat the oven to gas 6, 200°C, fan 180°C. Using kitchen scissors, cut the poussin in half lengthways. Mix the saffron into the butter along with a large pinch of salt and plenty of cracked black pepper. Smear it over the poussin skin.
Place the poussin in a small, lined roasting tin, skin-side up, and roast for 15 minutes. Add the wine and the tomatoes to the tin and roast for a further 15 minutes, until the tomatoes are blistered and the poussin is golden brown.
Meanwhile, make the mash. Chop the potatoes into evenly sized chunks. Boil in salted water for about 15-20 minutes, until tender.
Drain and return to the pan over a low heat. Allow to steam-dry for a few minutes, shaking occasionally. Tip into a bowl and mash.
Warm the butter and milk in the potato pan and add to the mash, beating with a fork until it's fluffy. Season to taste.
Serve the roast poussin halves with the warm mash and tomatoes, drizzled with the juices from the roasting tin.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home.