Lady Louise set to be with the Duchess of Edinburgh at major event before travelling to Scotland

Sophie will likely be joined by her husband, the Duke of Edinburgh, and their two children - Lady Louise Windsor, 21, and James, Earl of Wessex, 17, for the milestone occasion.

The family is anticipated to gather at their Surrey residence, Bagshot Park, for the celebrations.

Lady Louise Windsor, currently in her third year studying English at St Andrews University, will be able to attend her mother's birthday celebrations.

The timing works perfectly as the spring semester at the Scottish university doesn't begin until January 27, a week after the Duchess's birthday.

Lady Louise has been studying at St Andrews since September 2022, when she left the family home to pursue her degree in Fife.

James, Earl of Wessex, is currently believed to be in his second year of A-Level studies.

The family's residence at Bagshot Park in Surrey serves as their main home, though Lady Louise spends much of her time away at university.

The young royal has maintained a presence at key family events, appearing at Trooping the Colour, the Royal Windsor Horse Show and Christmas at Sandringham last year.

Sophie previously spoke about her children's future in a 2020 interview with The Sunday Times, stating: "We try to bring them up with the understanding they are very likely to have to work for a living."

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Lady Louise has balanced her studies with select royal appearances, including joining her mother at The London International Horse Show.

While many students complete university in three years elsewhere in the UK, Scottish degrees typically span four years.

According to St Andrews University's website, the first two years provide broad subject understanding, while the final two "Honours" years allow for specialisation.

Lady Louise is not expected to become a working royal after completing her education, following her parents' wishes for their children to pursue independent careers.