Preheat the oven to 170 C, Gas 5.
Season the turkey crown, place in a deep roasting tray with a 4cm gap around the edge.
Pour in the boiling stock, add the white wine, cover tightly with foil and place on the hob. Turn the heat to high and bring to the boil, you will hear the stock bubbling inside. Then carefully transfer to the hot oven for 1 hour.
Prepare the glaze, place the redcurrant jelly, horseradish and mustard in a bowl and whisk together to form a loose paste.
After the turkey has been cooking for an hour, carefully remove from the oven. Lift off the foil and using a skewer check to see if the juices run clear from the thickest part of the bird. Pour off the stock and turn the oven up to 200º C, Gas 7.
Spread the glaze evenly over the crown. Return to the oven and cook for a final 15-20 minutes to colour, making sure that it does not burn. Then remove from oven and allow to rest for 15 minutes before carving.
Meanwhile place the mayonnaise into a liquidiser with the watercress, a dash of vinegar and water then blitz to form a thick green puree. Season to taste. Transfer to a bowl for handing around the table.
Serve the turkey with roast potatoes and green vegetables such as broccoli or beans.
© Phil Vickery