Cook the beans in plenty of boiling salted water 1 1/2 - 2 hours, until tender.
Scoop out about half the beans with a slotted spoon, and using a stick blender puree the remaining beans in the saucepan.
In a separate large saucepan, heat a splash of olive oil and saute the carrot, celery and onion until soft.
Add the potatoes, cabbage and passata. Add the bean puree. Simmer about 40 minutes until the vegetables are well cooked.
Add remaining beans and cook another 15 minutes. Let cool about 15 minutes.
Slice the bread and start adding it to the soup, two slices at a time, stirring so it absorbs the liquid. Keep adding bread until soup is your desired thickness. Reheat the soup and serve with a drizzle of good olive oil.