Heat 2 tbsp oil in a large flameproof
casserole. Add the onion, celery and
bacon, then cook for 5-10 mins until
softened. Turn up the heat and add the
tomato purée. Cook for 2 mins, then add
the chopped tomatoes, sugar, mustard,
thyme, Worcestershire sauce and 200ml
water, then bring to the boil. Cook,
uncovered, over a low heat for 15 mins.
Add the beans and peppers, then simmer
for 15 mins more, topping up with a little
boiling water if needed.