Lightly toast the bread on both sides.
On one slice add 1/2 the mayonnaise and spread all over. Add the lettuce, egg, chicken and onion.
Place another slice of bread on top and spread with the remaining mayonnaise. Add the cheese, tomato, cucumber and bacon. Season well with salt and pepper.
Place the final slice of bread on top. Secure with toothpicks to help hold in place in each corner. Carefully cut into quarters, plate up and serve.