Drain the soaked peas, place in a saucepan, cover with fresh water and simmer 45 minutes.
Add the carrots, parsley, celery and leek.
Fry the bacon in a frypan. Add the onion and fry until soft. Add to the soup.
Add the potatoes. When the potatoes are tender make a roux by frying the flour and butter together then add to the soup to thicken. Season with garlic, marjoram, salt and pepper and simmer a few more moments before serving.