All-Aboard! How Queen Elizabeth Will Mark the Day She Breaks Her Great-Great Grandmother's Record

Her cousin calls it a "landmark", a palace staffer a “milestone,” but officially for Queen Elizabeth, her spokespeople say, it is “business as usual.”

That means riding a steam train from Edinburgh to a small station on the border area between Scotland and England as she opens a new rail line on Wednesday.

Like so much in royal life, there’s a symbolic significance to the outing that takes place on the day the Queen, 89, passes her great-great grandmother Victoria’s record of 63 years and seven months on the British throne.

“Victoria’s was the reign of the locomotive, and she was the first queen to go on the train,” says Ingrid Seward, author of the just-published [LINK” “” “” “0” ]. “It slots in well, as it is in Scotland, where she’s staying. She can spend time with the Scottish leader Nicole Sturgeon, and she’s doing something that [featured in] her great-grandmother’s reign.”

That parallel is also noted by fellow biographer Sally Bedell Smith, author of Elizabeth the Queen: The Life of a Modern Monarch, who says the train ride is due to Elizabeth’s “respect for Queen Victoria.”

“She is not going to do anything celebratory, but is going to do something neo-Victoria. It is so much in the spirit of the Queen in the way she is marking it,” Bedell Smith tells PEOPLE.

Seward believes that the Queen “is very humble, and she felt there were so many anniversaries with the end of the Second World War being marked, and so on and she would have felt that you can’t keep forcing anniversaries on people.” The deeply religious Queen will spend some of the day “in contemplation and prayer.”

Royal Flashback: Queen Elizabeth II’s Record-Breaking Reign

The monarch’s cousin Margaret Rhodes previously told PEOPLE that she wouldn’t “want a fuss made at all. She would regard it as inconsiderable. She wouldn’t spend much attention to it.”

But she is not surprised at the Queen’s longevity and praises her sense of duty. “She has kept the vow that she made to serve the nation when she was 21 in South Africa, which is most extraordinary,” Rhodes tells PEOPLE.

Insiders at the palace and Scottish government say it is not unusual for the Queen to carry out engagements periodically during her residence at Balmoral.

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