Pat the skin of the chicken dry and season with salt and pepper.
Stuff onion into the cavity and then tie legs together with kitchen string and then bake for 30 minutes.
Peel the carrot and roughly chop the leek and celery.
Place the chicken and remaining ingredients into a large pot and cover with water and bring to the boil and skim off any scum that forms and then cover and simmer very gently for up to 5 hours.
It will make your house smell wonderful.
Strain into a large bowl and allow to cool.
Chill overnight and then skim off fat that forms on the surface, use within 3 days or freeze.
SERVING SUGGESTIONS - the rich flavour of the wonderful broth makes a meal in itself, shred meat from the breast and throw in a handful of noodles and fresh herbs for a bowl of sublime chicken noodle soup.