Set your slow cooker to low. Tip in the onion, celery, carrots and leeks and nestle in the bunch of herbs. Sit the chicken on top of the veg and pour over the stock. Cook for 6-8 hours.

Remove the chicken from the slow cooker and transfer to a board. Shred the meat from the bones using two forks, then return the meat to the slow cooker, discarding the bones. Season to taste and stir through the lemon juice.

Remove and discard the bunch of herbs. Ladle the soup into bowls and top with the dill or parsley. Serve with crusty bread, if you like.