With scissors, cut off the gammon rind if any, and snip around the edges of the steaks at 25 mm f in intervals, to prevent them from curling under the heat. Heat the grill without the grid to medium.

Brush both sides of each steak with melted butter, lay the steaks on the grill rack, and cook for 4 minutes. Turn the steaks over, spread with mustard and grill for a further 3 minutes.

Arrange 1 or 2 pineapple rings on each gammon steak and brush with the remaining melted butter. Sprinkle the sugar evenly over the fruit and gammon, and grill for another 2 - 3 minutes, increasing the heat if necessary, until the pineapple rings are slightly browned and glazed.

Serve immediately, garnished with sprigs of watercress.