Rinse peas in cold water and then place in a large bowl, cover with cold water and leave to soak.
Place oil and bacon bones in a large saucepan and gently cook bacon bones for 20 minutes, turning at times.  Add the leek, onion, carrots and celery and gently cook, stirring at times until vegetables are tender.  Add peas and enough water to just cover.
Simmer gently until peas have turned to mush.  Add extra water if the soup is too thick.
Remove the bones from the pot and when they are cool enough to handle remove the meat.
Using a hand blender puree the soup until almost smooth.  Mix through the bacon meat and season to taste with salt and pepper.