While an advertisement is within its "useful period", its value is essentially limited to the company that produced it. It allows the company to have their name exposed to a wider audience. Being exposed to a larger audience allows a company more opportunities to create interest and generate income.
After an advertisement is no longer useful, it becomes useful to historians. Based on the photos on this particular poster, we can see that monarchs were much more widespread than they are today. They are also seen as the ultimate show of power and influence. The farm equipment used in the picture on the poster shows how the technology has changed in the last hundred years. At that time, the equipment was run by horses, now they are run by high powered motors.
The poster's value to me personally is one of emotional value. After so many weeks attempting to uncover its story and how it came to be, it has become a part of my academic life. I have spent countless hours researching its history and attempting to unearth its past. After spending so long with the poster, it will be tough to simply say goodbye to it once this project is completed.