Famed for salvaging £50m in gold from a shipwreck, adventurer Ric Wharton talks about selling his collection of historic armour

"A disastrous sell-off," he fumes, skilfully negotiating a narrow, leafy lane lined with banks of wild spring flowers. The wealthy Channel Islands-based businessman's annoyance with politicians isn't limited to the Labour government, however, since he also accuses the Thatcher regime and the Civil Service of being "mean, greedy, venal, jealous and dishonest", castigating them for obstructing the most ambitious salvage operation of the 20th century. And for not even sending a letter of thanks, in 1981, when he and partner Malcolm Williams's Aberdeen-based company restored 8m in gold bullion to the Treasury's coffers.

"They even made us pay 15 per cent VAT on it!

"It still rankles that we had to take a lesser share – 55 per cent of the gold was returned to the Soviets and 45 per cent came to us – but when it came to the British share of the 5.5 tons of gold we salvaged, we had to take a lesser split, although the government had contributed absolutely nothing to the operation, which was incredibly dangerous for our team of divers, because the wreck of HMS Edinburgh lay 840ft down in the Barents Sea.

"Undoubtedly, it was the greatest treasure hunt of the 20th century, because the Edinburgh's top-secret consignment of gold bullion was Russia's payment to America for supplies that a convoy from the west coast of Scotland had just delivered to help Stalin keep the Germans from the gates of Moscow," explains Wharton. The Edinburgh had escorted that convoy to Murmansk.

"On 30 April, 1942, the heavy cruiser was torpedoed by a German submarine. Although 750 crew members' lives were saved, 57 officers and men died," he adds, neatly ducking and diving when pressed to reveal exactly how much they got. "We did well out of the operation," he concedes, "although we spent about 3m on the job."

Meanwhile, he's doing some selling off himself – he's about to auction off items from his extensive collection of arms and armour in Edinburgh. They include ancient weapons, such as canons, blunderbusses and even a medieval jousting lance, in addition to marine memorabilia associated with that daring salvage operation.

There's no gold on offer, though. Wharton, who sports a white Captain Birdseye beard and wears a gold "" symbol in the lapel of his cardigan, doesn't own so much as a wee gold bar, although he and Williams gave all their divers specially made ingots, mementoes crafted by Wharton's jeweller brother.

He doesn't get emotional about the metal, anyway, only about the fact that, when he was chancellor of the exchequer, Gordon Brown lost 6bn selling off this country's gold. So, It's a bit like being trapped in a 4x4 with a party political broadcast on a constant loop – the 66-year-old engineer stood unsuccessfully for the Referendum Party for Aberdeen South in 1997, but today despairs of all politicians, who have, he sighs wearily, "taken the great out of Great Britain".

In Aberdeenshire, Wharton is known as "the Baron of Midmar", a reference to the splendid 16th-century Inverurie castle he and wife Jackie bought almost 40 years ago and have lovingly restored and refurbished, doing much of the work themselves, before gifting it 12 years ago to their four grown-up children. Their two sons and two daughters, whose ages range from 28 to 38, have put it for sale, asking for offers over 3.5m.

"The kids are scattered all over the world, so they can't live in it and it costs a fortune to run," says Wharton, who prefers the balmier climate of Guernsey to that of Aberdeenshire, much as he loves Scotland.

"I'm not a Scot, but I might as well be because I've spent more than half my life there," he jokes.

Before the turreted, towering Midmar – the only one of the five great castles of Mar still in private ownership – is sold, though, Wharton is clearing out his arms and armour, bidding a farewell to arms. It was a passion he could indulge, because he had a fortified castle in which to show it all off. He'd have liked someone to have bought it all along with the building, but is resigned to the fact that many of his historic pieces have to go. "It's painful to see it go."

There's no room for them in his Guernsey home, which is full of marine artefacts – including a model of HMS Edinburgh in his office. "Arms and armour are a nightmare to dust. I know it's a gory subject, nonetheless it's interesting to find out how many different ways people have devised for killing each other."

On 21 April, Edinburgh auctioneers Lyon & Turnbull will hammer a rare English bronze cannon – estimated to fetch 8,000 – as well as a 1983 model of MV Deepwater 1, the shipyard diving-support vessel used in the gold bullion salvage operation, valued at 1,500; suits of armour, double-handed swords, revolvers and pistols. Indeed, anyone who thrills to a theodolite, or covets a crossbow, or hankers after a halberd, will be beating a path to the 196-lot sale, points out the aptly named auctioneer, Campbell Armour.

Over a plastic cup of coffee in his office above his chandlery, which on a clear day has views across the English Channel to France, Wharton explains the background to "the salvage of the century", which remains the defining event of his life. "It was the maritime equivalent of a moonwalk," he says of those golden years, before adding that it's also a tragic tale of greed, mystery and intrigue.

It's so exacting that he's written a book about it, The Salvage of the Century, published in 2000 but only in the United States. The marine salvage superstar is still looking for a UK publisher.

After recovering 93 per cent of the Edinburgh's cargo – 431 of the 465 gold bars – Wharton and Williams called a halt to operations. Later, they asked permission to recover the other 34 ingots. After years of stonewalling from the government, they returned in 1985. They ended up salvaging 29 bars – no-one knows what happened to the missing five bars of gold.

"Good luck to whoever got them, although at the time I'd have made the culprit walk the plank. The great adventure was over," says Wharton, who was educated at St Albans School in Hertfordshire – "the oldest school in the country, dating back to 999," he says proudly – and Imperial College, London. After qualifying as a maritime civil engineer, he was drawn to the North Sea oilfields, hence the move to Aberdeen in 1973. He'd became fascinated by the sea after winning a school prize: a book by the legendary undersea explorer Jacques Cousteau, who inspired him to take up diving at university. Guns were yet another passion; in the school lab, he made explosives. "My elder brother made a crossbow and rockets, but we had a terrible accident when we were ten and 11," he recalls. "We blew the shed up, nearly killing him. It took his thumb off and wrecked his right hand, although he went on to become a world-class jeweller. I was blown into the rhubarb patch."

His has been a life packed with incident and adventure. In 2003, Wharton escaped from a plane crash, when the Cessna he was in crashed at Humberside Airport and burst into flames. Wharton dislocated his shoulder, but his Saudi Arabian flight examiner, Majid Ali Kabbani, died later.

Wharton dislikes talking about the tragedy. "It's a miracle anyone came out of it alive. I still have nightmares about being trapped in burning wreckage. I was always frightened of flying before I began to fly myself. I flew for years and years, but when you've seen how an aircraft comes apart and burns, you realise how fragile the whole thing is. Now, I'm a very nervous passenger – and there's no question of me ever piloting a plane again."

He still loves to dive, though, but only in warm, tropical waters. He says: "The sea around Guernsey is too bloody cold. If only Midmar Castle were in the south of France, I'd never have let it or the collection go."

The Midmar Castle Collection of Fine Arms and Armour will be auctioned by Lyon & Turnbull, 33 Broughton Place, Edinburgh, on 21 April.

Famed for salvaging £50m in gold from a shipwreck, adventurer Ric Wharton talks about selling his collection of historic armour – and leaving Scotland