1. Butter each slice of bread well.
2. Place 4 slices of cucumber on 3 bread slices.
3. Layer each separately with a second slice of bread.
4. Spread the diced chicken on this.
5. Cover with the third slice of bread.
6. Slice each triple sandwich diagonally to make 6 sandwiches.
7. Serve with ketchup.
Note: If you do not want a double decker sandwich, remove one bread slice and adjust the slices of cucumber accordingly.