A pair of Antiques Roadshow guests were urged to take urgent action following their visit to the Firstsite contemporary art gallery in Colchester, Essex during Sunday's episode.
The BBC staple welcomed the granddaughter and son of WWII Flight Lieutenant William McTurk to the programme where they had an array of the soldier's wartime items for Mark Smith to analyse.
McTurk's medals and treasured items bore an extra layer of significance to collectors as his relatives explained he was a prisoner of war at the time of 'The Great Escape' in which several soldiers devised an exit plan from the German POW camp, Stalag Luft III.
McTurk bore witness to the feat and Smith was keen to learn more about what his family members had brought in to be evaluated.
"What I can tell from your side of the table is he's a pilot, he's also a prisoner of war and at some point, his life has been saved by a parachuter," Smith analysed.
The Antiques Roadshow expert then explained what each of the soldier's medals were awarded for and what each of his badges signified before turning his attention to the Wartime Log.
BBC Antiques Roadshow: Mark Smith evaluated a series of WWII medals
BBC
"What happened to him?" Smith asked, prompting the granddaughter to explain: "He was shot down and he ended up in Stalag Luft III in February 1944 and he would've arrived there just before some of the activities for The Great Escape."
McTurk's son then chipped in: "He didn't talk about it very much. I think it was very private to him.
"We watched the film, of course, he spent the film saying, 'That wasn't right', or, 'It didn't happen that way' and all the rest of it."
After sharing a laugh, Smith then opened the log book to read its contents, unearthing some key entries and dates in the soldier's life.
BBC Antiques Roadshow: Mark Smith spoke with the soldier's granddaughter and son
BBC
Smith then picked up a tag given to McTurk upon his arrival as a POW at Stag Luft which included the name of the camp engraved on it.
In one of the books, Smith was gobsmacked when he discovered a hand-drawn plan of the tunnel that the soldiers used to flee.
The conversation then turned to the collection's worth, with the female guest revealing it was too "personal to the family" ever to contemplate selling.
Nevertheless, Smith was keen to put a price tag on the collection but insisted the pair take action before ever deciding to sell.
He explained: "A few years ago, a clasp came out for those who were in Bomber Command. And you don't have that.
"So you need to apply for that clasp from the Ministry of Defence because his medals are not complete now without that clasp," he demanded.
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BBC Antiques Roadshow: Mark Smith urged the relatives to apply for a clasp from the Ministry of Defence
BBC
He then pointed to a few of the items and said: "If you had that group of medals and not this part of the table, you'd probably be looking at somewhere in the region of £1,000 maybe £1,500.
"But you add this [the German tag] and this [the hand-drawn tunnel plans] and I think you go from £1,000 to £8,000, maybe £10,000. That in itself puts us there in that camp and in that film. It's a pleasure to meet him."
Speaking to the camera on his own soon after, Smith said: "The dog tag. You do see a lot of them from World War II but you don't see ones that says 'Oflag Luft 3'. So, Stalag Luft III, The Great Escape.
"So that is a really incredible thing, which puts that man in that camp that we know so well from that film, The Great Escape. It's a real treat to hold one."
