A Rolex watch bought for £70 and which featured on the BBC's Antiques Roadshow could fetch more than £45,000 at auction.
Peter Barnett, 57, inherited the timepiece from his father Simon Barnett just before he died in 2019, aged 80.
The historic 1963 Rolex Submariner watch was bought by Simon, a Royal Navy search and rescue diver, while deployed in Singapore in 1964.
It remained on his wrist throughout his 23-year career, helping him keep track of time while he was involved in several dangerous rescue missions.
Peter has decided to sell the watch after experts on BBC's Antiques Roadshow last year valued it at between £50,000 and £60,000.
Peter, from Diss, Norfolk, said: "The watch is very precious to our family and it's not a fashion piece – it was involved in a number of important rescue missions.
"It's been a hard decision, but I feel selling it now is the right thing to do."
While bittersweet, the appearance on the BBC show helped Peter piece together more of his father's career in the navy.
After the show a number of former servicemen also got in touch to share their adventures with him.
The watch can be seen in countless photographs taken of Simon during his time in the Royal Navy, capturing its place in naval history.
The sale at TW Gaze auction rooms on Friday is accompanied by several newspaper cuttings, letters and images - with the lot carrying an estimate of between £30,000 and £45,000.
Antiques Roadshow treasures
First Olympic medals won by a British black athlete sell for £8,000
The first Olympic medals won by a British black athlete were sold for £8,000 – more than twice their estimated value.
Runner Jack London made history when he scooped bronze in the 4x4 100 metres relay and silver in the 100 metres sprint in the 1928 Olympics.
The 23-year-old’s uncle John Downham also gold-plated an Olympic commemorative medal to “create a full set” for his talented nephew.
Downham’s daughter, Christine Downham, 60, took the memorabilia along to the Antiques Roadshow and experts said the items were worth at least £3,500 but they sold for more than twice their estimated value in 2019.
Battered storage box bought by a dad for £12 sells for almost £10,000
A battered storage box bought by a dad for £12 at a junk shop 40 years ago sold for more than 600 times that price after it turned out to be a rare Louis Vuitton.
He snapped up the trunk from a bric-a-brac shop in the village of St Margarets, near Twickenham, London, in 1984 for his daughter Melissa to use as storage.
Melissa took it along to the Antiques Roadshow last year and was stunned to learn it was 100 years old and worth thousands of pounds.
The 56-year-old decided to sell the designer trunk and was left stunned when it fetched almost £10,000 last August.
Queen Victoria's hand-sewn knickers worth thousands
A pair of Queen Victoria's hand-sewn knickers which featured on Antiques Roadshow were put up for sale for thousands of pounds at auction.
The rare pair of knee-length bloomers, with a single button and drawstring 40-41 inch waist, were even embroidered with a Royal Crest.
They were thought to have been passed down by a Lady of the Bedchamber who worked for Queen Victoria.
The pants were put up for sale at Lawrences of Crewkerne in Somerset on 19 April last year for an estimated price of £5,000 to £7,000 but were not sold after the bidding only reached £2,039.