Prince William held talks with former Prime Minister Gordon Brown, who has launched a campaign to save the union between Scotland and the rest of the UK, it has emerged.
William and his wife Kate have completed a week-long charm offensive in Scotland where they travelled up and down the country to mark the prince's appointment as Lord High Commissioner in the General Assembly of the Church of Scotland.
It emerged on Thursday as the couple finished their visits, that William and Kate had joined Brown and his wife Sarah for talks at the Palace of Holyroodhouse, the Queen's official residence in Scotland.
Brown has recently launched a think tank called Our Scottish Future which he has said will be a campaigning movement to appeal to "middle Scotland" - those not entrenched in a position of supporting either Scottish independence or remaining part of the UK.
Brown was a key part of the No campaign during the 2014 Scottish independence referendum.
A spokesperson for Kensington Palace said: "During his time in Scotland Prince William has spoken to a broad range of people from different communities including politicians from across the political spectrum."
Channel 4's Krishnan Guru-Murthy said teams from the broadcaster had spotted Brown leaving the palace in Edinburgh but was stopped from running the footage.
William's meetings in Scotland included talks with First Minister Nicola Sturgeon at the weekend and Alistair Carmichael, the Liberal Democrat MP for Orkney and Shetland, when he was on the islands.
The Duke and Duchess of Cambridge's trip, which was delayed from last year because of the coronavirus pandemic, was considered something of a charm offensive and hoped to bolster support for the United Kingdom.
Sturgeon's Scottish National Party has been celebrating a landslide victory in the May election at Holyrood, and calling again for a vote on Scottish independence.
Although the leader did hold talks with William, she did not share anything of them on her Twitter account, though she did say it was a pleasure to go to the opening of the General Assembly, which was the prince's first engagement.
In December, Sturgeon voiced frustration at William and Kate's train tour which brought them into Scotland, suggesting it was not essential travel.
Watch: Prince William and Kate Have a Ball on the Tennis Court
William bookended his trip over the border with emotional speeches showing his connection with Scotland. On arrival, he said: "Scotland is incredibly important to me and will always have a special place in my heart.
"I’ve been coming to Scotland since I was a small boy. As I grew up, I saw how my grandmother relishes every minute she spends here.
"And my father is never happier than when walking among the hills.
"My childhood was full of holidays having fun in the fresh air and swimming in lochs, family barbecues with my grandfather in command, and yes - the odd midge."
And speaking about the memorable people he had met along the way as he left, he said: "These people make Scotland the vibrant, friendly, innovative and determined place Catherine and I love, and is so important to us."
He added: I am shaped by this place. The abiding affection I feel for it is rooted in my experience of its everyday life - in people, relationships, and its ethic of neighbourliness."
He and Kate delighted the residents of Anstruther on Wednesday when they popped to their old favourite fish and chip shop for lunch in between engagements, revisiting their university haunts.
The couple met at St Andrews University in 2001.
Commentator Jenny Hjul said in The Courier: "The fact that they have such a strong Scottish back story makes them the ideal royals to despatch north when Scots need reminding what binds the United Kingdom together."
She added: "In the wake of an election that secured five more years of Scottish Nationalist bellyaching about independence, now is a good time to play the Windsor card, which still resonates with the majority here."
But Kevin McKenna wrote in The National that the royals used Scotland as a "tartan Disneyland".
He said: "While Scotland remains in the Union, its large extended family is given the most picturesque half of the country to shoot animals, ride horses, walk their dogs and fish in some of the world’s grandest waterways. And all without having to encounter too many actual Scots and their unpredictable ways and rough manners."
During the last referendum, David Cameron, then prime minister, had to apologise for saying the Queen "purred down the line" after he told her the nation had voted to remain in the UK.
Before the vote, she had reportedly said she hoped Scottish people would "think very carefully about the future".
But Buckingham Palace denied reports she was increasingly concerned about the prospect of a Scottish breakaway. The Queen is expected to remain politically neutral and has never voted.