Place beans in saucepan with lightly salted water. Bring to the boil; cover and cook for 1 hour, or until tender. Reserve.
Combine butter and oil in a large frying pan and sauté diced bacon and onion until onion is transparent. Add prepared carrots, baby marrows and celery and continue to cook, uncovered, for 3 or 4 minutes, stirring occasionally.
Pour over hot beef stock and simmer uncovered until almost all the liquid has evaporated. Add rice to this mixture and cook for 2 minutes, stirring occasionally, over low flame.
Drain beans, reserving stock. Add beans to rice, together with