Everyone is Essential
The Ladderless Window-Cleaning Company is dependent upon each member of the team doing the job they do best. The giraffe is essential because of height. The pelican is essential because of the volume of the beak. The monkey has balance and agility. Each of these animals is celebrated for the specific and individualized trait they bring to the operation. If any one of them becomes unavailable, it is not so much a question of whether they will be able to do the job as whether they would be able to find a replacement.
Obviously, there are plenty of humans around who could take up the slack, but would they bring the same abilities to the job? Likewise, take the giraffe, pelican or monkey away from their business, where else could they go to use their gifts to the fullest advantage? On one level, the book is a thematic celebration of single-use potential with the implicit message being that while some people may be less than useful in most situations, there is always some kind of situation out there where they would be essential.
Diversity
The story is also a celebration of diversity. The window-cleaning company is comprised of three completely different sorts of animals. Eventually, a young boy and a rich and titled adult British gentleman also become essential elements of the union. Not only are the animals unlike each other, but they are not native to any one place. If the story was told using human beings, they would undoubtedly represent distinctively different nationalities and ethnicities and working together.
Teamwork
In addition to celebrating the essential quality of every individual, the story also pursues the theme of the importance of teamwork. Even though each member of the team brings a unique ability to the operation, the job of actually cleaning the windows could not be done if they did not work in tandem to exploit the efficiency of those unique abilities. While each is essential, no one single part of the team is more vital than the other.
Hard Work Pays Off
While hired to clean the more than six-hundred windows on his mansion by the Duke of Hampshire, the window-cleaners spot an armed burglar inside trying to steal the jewels of the Duchess. The heist is thwarted by the intervention of the animals, most notably by the pelican who traps the burglar inside the pouch of his beak. The animals are rewarded by the Duke for their heroic action, while the burglar is punished, thus proving that success comes to those who work hard rather than those who try to take the shortcut to riches through crime.
