Brown the thighs in some of the oil for 5 minutes. Add enough boiling water to cover (and a chicken stock cube if you have one handy) and let simmer for 1 hour. Fish out the chicken and put to one side.
Five minutes before your chicken has finished simmering, put the diced potato, carrot, and chopped leek and some of the parsley into a pan on a medium heat. Cook them for10 minutes until they soften.
Add the chicken juices and some bay leaves to the vegetables. Bring to boil and then reduce to simmer. Season with salt and pepper. Let cook for 30 minutes.
Add the chicken. Cook for 10 minutes more.
Add the rest of the parsley and the double cream and stir. Continue to cook for 10 minutes.