Boil the chicken until fully cooked, but don’t let it overcook or it will be too dry. Peel off the skin and shred the cooked chicken into small pieces – best accomplished with your hands by breaking it apart. Cut the white cabbage into long thin strips. Put in bowl, then cover with the malt vinegar and boiling water to soften. After 5-10 minutes, drain and put to one side. Boil the carrots and potatoes. Then once cooked through, roughly dice into cubes. In a big bowl, mix the chicken, diced potatoes, carrots, petit pois. Add the shredded cabbage. To make the dressing, mix the mustard, salt, pepper and mayonnaise into the bowl and gently combine until it is evenly distributed. Refrigerate until needed. Will last in the fridge for 1 to 2 days.