Preheat oven to 210 degrees Celcius.
Bake the bones in the oven for 30 minutes, turning occassionally. Add carrot and onion to the pan and continue to bake for a further 20 minutes. Transfer to a large stockpot discarding all the fat.
Add water and celery to the stock pot. Slowly bring to the boil skimming the surface with a slotted spoon to remove any scum. Stir in the herbs and peppercorns. Reduce heat to low and simmer gently for 4 hours, skimming the surface regularly.
Strain the stock through a fine sieve gently pressing solids with a spoon to remove excess liquid. Discard bones and vegetables. Allow to cool and refrigerate until cold. Remove all set fat from the surface.