Preheat oven 180˚C and put the oven shelf to the lowest position.

Peel the skin away from the ham using a sharp knife, leaving a thin layer of fat on the surface.

Transfer the ham into a large roasting pan, or if too big onto a large baking tray.

In a small saucepan over low heat cook the marmalade and sugar until combined.

Glaze the ham. Arrange the orange slices, overlapping, on top.

Secure each slice with a toothpick if needed. Brush with a little more glaze.

Bake for 1 hour and 20 minutes. Brush occasionally with remaining glaze.

Serve hot or cold