Preheat the oven to 180°C / 350°F / Gas mark 4.
Line a baking tray with greaseproof paper then set aside.
Bring a pan of water to the boil and prepare a bowl of iced water at the ready.
Cut a small slit in the bottom of each tomato then plunge them into boiling water in batches for 10 seconds then lift out into the iced water.
Drain and peel the tomatoes then halve and place on the baking tray cut side up.
Sprinkle with salt, pepper and the sugar.
Drizzle with the vinegar and 1 tablespoon of the olive oil.
Roast the tomatoes for 1 hour and set aside.
Heat the remaining oil in a large saucepan and cook the onion and carrot gently for about 10 minutes until very soft.
Add the garlic and tied herbs and cook for a minute more.
Stir in the tomato purée then tip in the roasted tomatoes and any juices from the tray.
Pour over the stock and season with salt and pepper.
Bring to the boil then turn the heat down and simmer for 10 minutes.
Remove the tied herbs and discard.
Add the double cream then take off the heat, blitz well in a food processor until smooth.