Pre-heat the oven to 180ºC/350ºF/Gas mark 4

In a large bowl or food processor mix the flour, suet and salt

Add the cold water and combine to form a stiff dough

Dust a work surface with flour and roll out the dough into a rectangle

Liberally spread the jam leaving a 1cm gap along each edge

Roll up along the short side and brush the long edge (and ends if desired) with milk to seal

Grease a large baking tray and put the roly poly on it, putting the join at the the bottom

Brush the top with milk and sprinkle with a little granulated sugar

Bake in the oven for 30 minutes

Allow to cool slightly on a wire rack before serving with custard