A letter from Princess Diana with the scrawled signatures from young Princes William and Harry has emerged for sale for £18,000.
The handwritten note from the Princess was to thank a police sergeant for putting on a motorbike display for William's birthday party.
The boys, then aged seven and four, added their names to the bottom -
William's in joined-up writing and Harry's with larger, separated letters.
The unity is a far cry from the rift which is currently tearing their relationship apart.
The brothers have reportedly barely spoken since Harry, now 38, and his wife Meghan, 41, quit as senior working royals and moved to the US in March 2020.
Sgt George Plumb of the Metropolitan Police and the Special Escort Group put on the dazzling display for William, Harry and their friends on the grounds of Kensington Palace in 1989.
Diana's letter is dated June 21, 1989 and written on Kensington Palace headed paper.
It reads: "Dear Sgt Plumb, It was so very kind of you and your team to have come here today on William's birthday - I cannot begin to tell you what pleasure the display gave to all those little people and their mothers!
"I know how particularly busy you all are at the moment, so it meant even more to us that you and the motorbike boys were able to take part in the birthday celebrations!
"This comes with our warmest possible thanks. Yours sincerely Diana, William, Harry."
The comment about the team being "busy" refers to the fact there was public transport workers' strikes taking place in London at the time, affecting rail, underground and bus services.
The letter is being sold by auctioneers William George, of Peterborough, Cambs.
A spokesperson said: "This letter comes personally signed by Diana Princes of Wales, H.R.H Prince William and H.R.H Prince Harry, dated 21st June 1989.
"It is on Kensington Palace headed paper, addressed to Sgt George Plumb Special Escort Group in Diana's handwriting.
"It thanks Sgt Plumb and his team who put on a superb display by the Precision Motorbike display team of the special escort group, for Prince William's 7th Birthday.
"She was particularly grateful to the team for being able to fit this on a day already full of official engagements, which was not helped by the rail,
underground and bus strikes, something which strikes a chord with today.
"To have an item signed by Diana, William and Harry is quite special."
The letter left Sgt Plumb's estate six years ago when they were bought by a private collector. It is now being sold again at auction which takes place on January 10.
