Her Majesty Queen Elizabeth II grins for the camera as she opens a new railway line between Edinburgh and Tweedbank on Wednesday.
Resplendent in a two-tone turquoise and appropriately royal blue outfit by one of her favourite designers, Karl Ludwig, the Queen underplayed the real importance of the day.
At around 5.30pm, she overtook her great-great-grandmother, Queen Victoria, as the longest reigning British monarch.
Barely acknowledging the event, she said in her speech - attended by Scottish First Minister Nicola Sturgeon: "A long life can pass by many milestones; my own is no exception."
She added: "Many, including you, First Minister, have also kindly noted another significance attaching to today, although it is not one to which I have ever aspired."
It was noted, however, that on that day Her Majesty chose to accessorise her outfit with one of Queen Victoria's bow brooches, inherited from her ancestor, who reigned for 23,226 days until her death on January 22, 1901.
Princess Elizabeth became Queen Elizabeth II in the early hours of February 6, 1952 on the death of her father, King George VI.
At the time, Elizabeth and her husband, Prince Philip, were in Kenya - a stop-off on their way to tour Australia and New Zealand.
It was Prince Philip who broke the news to the new queen, who chose to keep her given name Elizabeth for her reign.
She was crowned at Westminster in 1953.
Historians estimated that Elizabeth would overtake Victoria at around 5.30pm on September 10 and the palace and Government happily agreed with this.
The House of Commons suspended parliamentary business to issue statements of congratulations, while on the Thames a celebratory flotilla made its way up river. The Queen reigns over 16 countries, including the United Kingdom, Australia, Canada and New Zealand, while also acting as head of the Commonwealth, made up of 53 countries.
During her extraordinary reign, the Queen has become the most travelled monarch in the world, with 97 state visits, and has had 12 prime ministers serve under her.