Princess Anne was left waiting 40-minutes for Shona Robison, the Deputy First Minister of Scotland, in a move that has sparked a furious backlash against the SNP.
The Princess Royal was north of the border on Friday to open the Aberdeen South Harbour on behalf of the Scottish Government, and Humza Yousaf's second-in-command was scheduled to attend.
However, it is understood that Robison kept the 350 guests and Princess Anne waiting 40 minutes before she arrived.
The Princess Royal was said to have spoken to guests for longer than intended in order to fill up the time.
WATCH NOW: Princess Anne being the 'hardest-working royal'
The Deputy First Minister then shocked the audience by choosing not to thank Anne for attending, unlike the UK Government representative Andrew Bowie who did.
But Robison did apologise to the organisers for being late, which she blamed on "urgent government business".
According to reports, Princess Anne was due to arrive at 1.30pm and then meet guests at 1.50pm.
The politicians in attendance, Robison and Bowie, were then meant to give their speeches at 2.35pm.
Princess Anne is frequently called the 'hardest-working royal'
PA
Shona Robison did not acknowledge Anne in her speech
PA
Guests who attended the event told The Mail that the speeches did not begin until 3.05pm, which was caused by the Deputy First Minister's late arrival.
Douglas Lumsden, the Scottish Conservative MSP for North East Scotland, wrote on X, formerly known as Twitter: "Totally disrespectful that the Deputy First Minister kept everyone waiting, including Princess Anne, at the open of Aberdeen south harbour.
"Even worse, Scottish Government officials originally claimed she wasn't late!"
One royal fan posted on the social media platform: ""The SNP are just petty. Arriving 40 minutes late for the hardest-working member of the Royal Family. Student politics is alive and well in the SNP.
"I hope Princess Anne made a put-down comment to Robison when she eventually arrived!"
Shona Robison is Humza Yousaf's Deputy First Minister
PA
Another X account said: "I’m not what you call a fan, but Princess Anne is the one royal who has contributed more to the whole country.
"A respected no-nonsense person, an Olympian who along with her immediate family has represented the country in many equestrian events. Robison is an embarrassment."
"Princess Anne has such class not to mention manners compared to any SNP MSP," another royal watcher added.
LATEST ROYAL NEWS:
Princess Anne filled the time by speaking to attendees
PA
One social media user wrote: "Robison must state what was the 'urgent government business' that justified her leaving attendees, including HRH Princess Anne, waiting 40 mins to open Aberdeen South Harbour. Robison’s tardiness smacks of a deliberate and studied disregard to all."
A Scottish Government spokesman told The Mail: "The Deputy First Minister was unavoidably delayed due to urgent Government business and apologised to the organisers.
"The speeches were not delayed and the organisers were notified in advance."