I once had in my possession a photograph of King Carl Gustav of Sweden at a State Dinner at the Palace of Holyroodhouse in Edinburgh, but the book seems to have vanished. I did find a tiny pic online which, when blown up, shows both the Duke of Edinburgh and the Duke of Rothesay in full evening dress at the dinner. Unfortunately the photo is very blurry!

What it shows is the following;
HRH The Duke of Edinburgh is wearing a kilt of Royal Stuart tartan; a waistcoat of the Balmoral tartan; diced hose of red, green, and white; a "Windsor Uniform" coatee, ie. a doublet of dark blue cloth with scarlet cuffs and collar; buckle and strap shoes; sealskin sporran; black bow tie worn with a wing collar; decorations.

HRH The Duke of Rothesay is wearing a kilt of Dress Stewart tartan; a high buttoned red waistcoat; belt ( I cannot tell if he is wearing a dirk ); red and white diced hose; an open doublet with 4 or 5 buttons which looks to be collarless and either black or navy cloth; bukle and strap shoes; white sealskin sporran ( that would be BABY seal for all those concerned with PC! ); black bow tie worn with a wing collar; decorations.

Oh, and both of the Royal Dukes are wearing the Garter of the Order of the Garter below the left knee!

It is also worthy of note that while the dinner is white tie, full Highland dress allows for the wearing of a black bow tie.

Sorry about the poor quality of the photo!