What event led to the creation of the montage portrait of the Queen?

The montage portrait of the Queen was created in celebration of significant milestones in her reign, primarily the Jubilee celebrations. Jubilees mark notable anniversaries, such as 25, 50, or 60 years of service, and they are typically associated with grand celebrations and events that highlight a monarch's legacy. This particular context serves to honor the Queen's contributions and achievements over the years, making a montage portrait a fitting tribute to encapsulate her image and the public's admiration during such a momentous occasion.

In contrast, while a birthday celebration might commemorate her personal milestone, it does not carry the same national significance as a Jubilee. A coronation anniversary is an important event, but it focuses specifically on the day she was crowned, rather than her lengthy service overall. A national holiday could involve various reasons for celebration, but it generally does not specifically relate to an individual's accomplishments like a Jubilee does. Therefore, the Jubilee celebrations are rightly identified as the occasion that inspired the montage portrait.