Wash and peel the potatoes. Cut them into thick slices. Cut off the roots and leaves of the leeks and wash thoroughly and slice.
Put the potato and leek slices in a saucepan, cover with boiling, salted water, and cook for 8-10 minutes, until half cooked. Drain well.
Grease an ovenproof dish, put the vegetable mixture into the dish, and sprinkle with the salt and pepper. Chop the ham. Put the ham on top of the vegetables. Pour the chicken soup over the top, and heat through in the oven (400F/200C/Gas Mark 6) for about 20 minutes.
Wash and slice the tomato and place on top of the vegetables for the last 5 minutes of cooking time. Serve with hot bread rolls and butter.