Toast the bread, leave it to cool, then butter on one side only. Crack the eggs one at a time into a cup. Bring the water to the boil with a generous pinch of salt and the vinegar, reduce the heat, then slide the eggs one at a time into the gently simmering water.

Remove the saucepan from the heat and, using a broad knife, try to stop the egg white spreading too much. Return the pan to the heat.

As soon as the water begins to boil once more, remove the pan from the heat and leave the poached eggs to finish cooking in the hot water for 4 minutes.

Cut the ham into even strips. Lift the eggs out of the water, cut off some of the white to even up the edges and leave the eggs to cool.

When cool, place each egg in the centre of a slice of toast, surround with the ham and top each egg with a stripe of mayonnaise and a stripe of ketchup. Sprinkle the egg whites with the pepper.