Prince William has been installed as a Knight of the Order of the Thistle at a ceremonial service in Edinburgh.
The Duke of Cambridge , or Earl of Strathearn which is his official title in Scotland, was granted Scotland's highest honour by the Queen at a special ceremony at St Giles Cathedral.
The Queen was accompanied by the Duke of Edinburgh, the Princess Royal and Kate, the Countess of Strathearn.
Large crowds gathered on a foggy Royal Mile outside the cathedral hoping to catch a glimpse of Prince William and Kate. And they were not disappointed.
Kate, Countess of Strathearn, wearing an Emilia Wickstead golden yellow coat dress, smiled at the crowds lining the Royal Mile as she entered the cathedral.
American tourist Patrick Hagen, from Baltimore, told Sky News: "The history and the pageantry in this country is just incredible. To see the Queen, Prince William and Kate is just amazing. We love it. Kate looked so beautiful."
Eileen Pierce, from Edinburgh said: "With all the talk of independence here in Scotland it's just really nice to see all the Royal family here and to see royal tradition being played out for all to see.
"The Queen looked lovely and really happy."
After the service the Queen was guest of the Knights of the Thistle, who hosted lunch at the Signet Library. A special parade of 400 pipers then marched down the Royal Mile to the Scottish Parliament to celebrate the Queen's Diamond Jubilee.
The Order of the Thistle is second only in precedence in the UK to the Order of the Garter and honours men and women who have held public office or who have contributed in a significant way to national life.
The ancient Order can only be bestowed by the Queen and is a personal gift which does not require the approval of the UK Government - the Princess Royal was invested in the Order in June 2001.
Prince William has been granted the title as it is traditionally bestowed on those who have a direct line to the throne. The honour is purely symbolic and does not hold any powers.
The event comes as the Queen continues her annual week-long residence at the Palace of Holyrood in Edinburgh, which this year also marks her jubilee.
Her engagements have included a visit to the Scottish National Portrait Gallery in Edinburgh, an investiture ceremony and garden party at the palace and a special jubilee thanksgiving service in Glasgow.
The visit will conclude with engagements in Perth on Friday.