The 86-year-old captured some of the defining images of 20th century Scotland, including the moment when the Tartan Army tore onto the Wembley turf and snapped the crossbar after a 2-1 victory over England in 1977.
“I knew straight away I’d got a great shot,” he recalled decades later. “That picture has been published around the world - in fact, The Scotsman still sells copies of it.”
Thanks to his eye for a picture and his easy-going charm, he photographed and befriended some of the leading stars of the day, winning countless accolades along the way.
His career began at the age of 15, when he secured a job at his hometown newspaper, the Berwick Advertiser, for 25 shillings a week. When the other photographer on staff left, Denis laid claim to the unofficial title of the UK's youngest ever chief photographer.
He did not have to wait long for further honours. After serving in the RAF, he joined The Scotsman in 1957, beginning a partnership which would last for 42 years.
Throughout his career, Denis captured seminal images of the great and the good, including The Beatles, Marlene Dietrich, Brigitte Bardot, and a worldwide scoop of Elizabeth Taylor, taken just weeks after the death of Richard Burton. “That was the one time I was able to come into the office and shout 'Hold the front page!',” Denis later said. They did just that.
After covering more than 50 Edinburgh Festival seasons, he became a fixture of the city’s cultural life in his own right, and counted Peter Ustinov and Billy Connolly among his friends.
Yet the best picture he never took came in 1962, shortly after the release of Dr No, the first James Bond film. Denis was on the bus to work, when saw Sean Connery helping an elderly woman with her shopping along Fountainbridge. His camera, alas, was in the office.
Sport also proved fertile ground throughout Denis’s time at The Scotsman. He won an award for his work covering the Commonwealth Games in Edinburgh, and showed unerring commitment when informed that the prize was his weight in whisky.
"I had a couple of weeks before the award ceremony so I went on a diet - a diet of chips, beer, pies and more pies,” he later said. "I wore a full heavy dress kilt to the ceremony where I was weighed, and even stuffed the sporran with 50p coins.”
Mr Straughan was honoured by his peers in 2008 with a lifetime achievement award at the First ScotRail Press Photography Awards, with an exhibition of his work following soon afterwards.
Those who worked alongside Denis, and the generations of photographers he helped and inspired, were among those to pay tribute.
Hamish Campbell, a former chief photographer at The Scotsman, and a colleague of Denis for more than three decades, said: “He was an excellent snapper and a flamboyant character with his open-necked shirts. He was a great guy and he was known as Mr Festival for years.
“He was famous for his portraits, and I remember he got fantastic images of Shirley Bassey. She was supposed to be protecting her voice, but she was scrounging fags off him during the shoot.”
He added: “One time, Denis was covering a full-scale NATO exercise in Carnoustie, with land forces trying to stop craft coming in from the coast. There was a tripwire set out, and whichever side crossed would be declared the winner.
“The picture editor didn’t give him enough time to get up there, and so when he arrived, the exercise was in full swing, with soldiers in full camouflage gear running about. Denis was staggering about to find the best place to go, and tripped over the wire. There was an enormous smoke flare which went up, abandoning the whole thing.”
Wattie Cheung, the award-winning press photographer, who joined The Scotsman in the 1990s, found Denis to be a constant source of advice and encouragement.
“He would like to look over my prints on a table and say, ‘That’s a good one, son, aye’, or ‘That one’s no’ as good, but if you had done this, it would have helped’. He would never dismiss anything out of hand. I was in awe of him”.
Alan Murray, who worked as a printer in The Scotsman’s darkroom, also remembered an accommodating colleague, albeit one with a mischievous streak. “He always encouraged and looked on the bright side,” he said. “One day, he sneaked heavy stones in a photographer's bag before they left for their first job of the day.”
A keen naturist, Denis was a regular visitor to the Greek islands, where his fellow beachgoers never learned the secret of where he kept his cigarettes and lighter. The answer, it can now be told, was a ziplock bag, buried under the same rock each year.
In retirement, Denis remained immensely proud of his career, and a selection of his work has pride of place on the walls of Winstons, the Corstorphine bar he called his local.
Close friend Ian Cuthbert said: “Denis was a bon viveur and a raconteur. His work was his pride and joy, and his photographs are just remarkable.
“One time, he was photographing the royals at Holyroodhouse, and Princess Margaret obviously took a shine to him. She asked him if he was coming to a ball later that evening. Denis replied: ‘Margaret, there will be other men there’.“
Denis, whose wife, Irene, passed away several years ago, is survived by his son, Kevin, his grandchildren Rachel and Scott, and his great-grandson, Luca.