Pre-heat the oven to 200°C, 400°F, Gas Mark 6.
Place the mushroom soup, lemon juice, mayonnaise, onion, Cayenne Pepper and Parsley in a large bowl and mix well. Add the turkey, celery, chop 2 of the eggs and stir them into the prepared sauce.
Place the mixture in a shallow casserole dish. Crush the crisps and sprinkle them over the casserole to cover the mixture completely. Bake in the oven for 30 minutes.
Garnish the dish with slices of the remaining egg and sliced tomato. Serve with a tossed green salad or green vegetables for a quick and easy main meal. This dish is not suitable for freezing.