Preheat the Aga ovens. Scrub potatoes and lightly pierce with a fork several times.
In a bowl, combine water and salt, stir until the salt has dissolved. Toss potatoes in the bowl until evenly coated with salt water this ensure the potatoes are coated with salt and help create a better crust.
Place potatoes on a tray or directly on the oven rack and transfer to the roasting oven. place on the third set of runners. Leave for 65-100 minutes depending on the size of the potato. ( 40-45 minutes for medium potatoes, 25-35 minutes for small )
After 30 minutes, brush the potatoes with oil and continue to cook until soft when pierced with a fork.
Take potatoes out of the oven and immediately cut skin with a knife in a criss-cross shape or straight so the steam can escape and serve with some crème Fraiche or sour cream and a sprinkle of chives.