Just one month after announcing their engagement, Peter Philips and Harriet Sperling have headed to Balmoral(Image: UK Press via Getty Images)

The King and Queen have been enjoying their holidays away at Balmoral for the last week, in a long-standing summer tradition started by the late Queen Elizabeth. They have been joined by select members of the royal family, with Prince Andrew and Sarah Ferguson even making the trip to Scotland for the family getaway.

Reports have now claimed that Princess Anne’s son Peter Philips and his new fiancé Harriet Sperling have also made their way to the Aberdeenshire property, where Sperling is undergoing the famous “Balmoral test”.

Philips and Sperling announced their engagement at the beginning of August, and now with a royal wedding to plan, Sperling is being thrown into royal tradition as she joins the family for their annual trip away before resuming royal duties in September. It comes as the royal family are keen to signal a united front while attending a Sunday service at church.

Peter Philip’s fiancé Harriet Sperling has joined the royals in Balmoral (Image: Getty Images)

Insiders have revealed that Harriet, an NHS nurse, has been immersed in the traditional family exam while in Balmoral, in preparation of marrying into the Firm. She has reportedly been bonding with her soon-to-be sister-in-law Zara Tindall and her children while enjoying rides on trips on electric-powered mountain bikes around the estates.

She also joined the royals while horse-riding in the estate, while spending more one-on-one time with each member of the royal family for valuable bonding sessions.

The Balmoral Test lives in folklore within royal circles, with Princess Diana’s wooing of the late Queen and Prince Philip even being immortalised in Netflix show The Crown.

A source told The Sun: “Everyone knows Peter is smitten and his family have accepted Harriett into the set up so she will likely pass the infamous Balmoral Test with flying colours.”

Princess Anne’s son announced his engagement to the NHS nurse on August 1st(Image: i5 Media)

Royal expert Omid Scobie previously described the Balmoral Test as more of a “royal initiation”, as he told Harper’s Bazaar before the death of Queen Elizabeth: “Out of those privileged enough to have been invited to  Balmoral Castle during the summer, not everyone has passed. Diana famously flew through it, thanks to her aristocratic background and upbringing, but the likes of Cherie Blair [the wife of former British Prime Minister Tony Blair] and Prime Minister, Boris Johnson, have not.

“If you’ve scored an invite, prepare to brush up on your royal protocol, have a wealth of talking points at the ready, an outfit for EVERY occasion (from hunting to black tie) and, most importantly, be on your best behaviour at all times. Social etiquette is a must! If you don’t like the food, eat it anyway. If you don’t like trampling through the Highlands in the wind and rain, tough! Unlike a visit to Buckingham Palace or Windsor Castle, this is the queen’s private residence and a front row seat within her inner sanctum.”

Peter and Harriet announced their engagement on August 1st after just one year of dating. A statement on behalf of the couple read: “Mr Peter Phillips, the son of HRH The Princess Royal and Captain Mark Phillips and Ms Harriet Sperling, daughter of the late Mr Rupert Sanders and Mrs Mary Sanders of Gloucestershire, have today confirmed their official engagement.

“Both families were informed jointly of the announcement and were delighted with the wonderful news of their engagement. Their Majesties The King and Queen, The Prince and Princess of Wales have been informed of the announcement. No date has been officially set for the wedding.”

Pictures by Hello! show the newly-engaged couple happily posing for the camera with Harriet showing off her diamond engagement ring. In July, the couple appeared at Royal Ascot together where Harriet made her debut in one of the carriages during the royal procession – with the move being seen as a significant sign of her moving into the royal fold.