Heat the grill to moderate. In a bowl, stir the curry powder into the mayonnaise and mix in the chicken. Lightly grill the bacon, drain well on absorbent paper and keep warm.

With a very sharp knife, remove the crusts from the bread and trim the slices to exactly the same size. Butter both sides of the white, and one side of the brown bread slices. Spread the chicken mixture equally over 4 slices of the brown bread. Top with the white bread slices.

Put a lettuce leaf and 4 slices of cucumber on each sandwich. Top with remaining brown bread slices.

Finally top each sandwich with the tomato slices and a grilled bacon rasher.