To make the ketchup:

First make roast tomato sauce:
Cut tomatoes in half, lay in a single layer on a baking tray.  Sprinkle with herbs, garlic, salt and a drizzle of oil.
Cook in oven at 180°C for about 1 hour until the tomatoes are beginning to caramelise.
Allow to cool, puree.  This can be used straight away or frozen.

To convert the sauce into ketchup:
For every litre of sauce, add 50g brown sugar, 50ml cider vinegar, 1/4 teaspoon ground mace, 1/4 teaspoon ground mixed spice, 2/3 teaspoon smoked paprika, 1/3 teaspoon hot chilli powder.
Simmer on a low heat until you like the consistency.
Bottle and enjoy.