Duncan left Stratahallan just last year and he went back to his former school to share with pupils his experiences of competing on the biggest sporting stage in South America in August.
The 19-year-old won silver medals for Team GB in the 4x100m and 4x200m freestyle.
His visit to Strathallan was a chance to reunite with his school swimming coach, Elaine Johnston, who coached him throughout his years at the independent school, as well as the various teachers who supported him in his formative years.
Duncan kicked off his visit by attending a question-and-answer session with all age groups.
The Olympian then visited his old dorm room as a boarder and enjoyed a session in the pool with Strathallan’s current swim team.
Duncan had a lot of fun during his visit and especially enjoyed being able to inspire pupils with his Olympic experiences.
“It has been great coming back to Strathallan to share my experiences of competing in Rio with the pupils and my former teachers,” said the teenager, who also made the podium while still a school pupil at the Commonwealth Games in Glasgow.
“Strathallan was always so supportive of me throughout the seven years I was here and it means a lot being able to give something back by returning and helping to motivate the next generation.
“I was just like the pupils here not so long ago and have many happy memories of my time here.
“Seeing Elaine, Miss Audrey Sime (director of sport) and so many other teachers has been really nice too.
“The teachers were brilliant while I was here, helping me to balance my school work and going to competitions. Nothing was ever impossible.”
Since Duncan departed Strathallan last year, Elaine has kept a proud and watchful eye on Duncan’s progress and is delighted to have welcomed the Olympian back to school for the day.
“Everyone has been so excited about welcoming Duncan back to Strathallan,” said Scotland’s former Commonwealth Games swimmer. “Duncan was just 11 when he first arrived at Strathallan and, from the minute he stepped into the pool, I knew he’d go far.
“It has been wonderful to see him perform so well – and he’s still only 19 years old, so his career is only just beginning.
“It has been fantastic for pupils to see him again and hear about his Olympic experiences.”