Chartered surveyor Thomas van Straubenzee, who was at school with the Prince, will tie the knot with Lady Melissa Percy, the youngest daughter of the Duke of Northumberland.
Even without the royal connection interest in the nuptials would be high since the bride's father is worth an estimated ₤320million.
Saturday's ceremony at St Michael's Church in Northumbria will be followed by a reception in Alnwick Castle, the Percy family's 1,000-year old seat. Dubbed the Windsor of the North, it featured as Hogwarts in the Harry Potter films. Celebrations will culminate in a spectacular fireworks display at 10pm.
Local police have been put on standby to maintain security while also allowing the public a good view of the 500 high profile guests expected.
With well-wishers expected to walk from the castle to the church, there will be plenty of opportunities for spotting well-known faces.
The wedding is to take place at her imposing family seat Alnwick Castle
The mother of the bride said the family "wants local people to feel this is their wedding".
"This is all about the loyal extended Alnwick family and we really want them to share in it," the Duchess told the local media. "But we don't want the guests to steal the thunder from the bride. This is all about Melissa and Thomas and we mustn't forget that."
Having attended Ludgrove Prep School and Eton with the Duke of Cambridge and Prince Harry, Thomas, 30, is very much part of the gilded royal set. He travelled to New Zealand together with the future King during their gap year.
When his brother Henry died, aged 18, in 2002 as the result of a car crash, the royals were very supportive and became patrons of a memorial fund in his name.
It was the setting for the nuptials of her sister Lady Katie, seen here with their father
The dashing aristocrat's friendship with the Queen's grandsons became headline news in 2011 when he was mugged while talking on the phone to Harry, who rushed to his aid with a police bodyguard.
Then, earlier this year Thomas and Melissa, 25, were guests at the wedding of Laura Bechtolsheimer and Mark Tomlinson in Switzerland, along with the Cambridges. It was during the festivities that expectant Kate was seen sledging.
The Duchess of Cambridge's sister Pippa Middleton was among guests
The bride and groom's ties with the royal set don't stop there. Melissa's brother George shared a house with Pippa Middleton at Edinburgh University. Meanwhile, Harry's ex-girlfriend Chelsy Davy is her confidant and is reported to be acting as chief bridesmaid.
In 2011, the glamorous pair were on hand when Melissa's older sister Lady Katie exchanged vows with financier Patrick Valentine also at Alnwick Castle. Those nuptials give some clue to what can be expected this weekend.
The bridal party travelled in the family's luxurious state coach, which was used at the coronation of Edward VII in 1902.