Seamus claimed bronze in the under-17 men’s 67 kilogram category in Leeds, where he was up against two Great Britain internationals.
He lifted 72kg in the snatch and 97kg in the clean and jerk for a total of 169kg - more than twice his 66.7kg bodyweight.
The 17-year-old, who trains at Diamond Weightlifting in his home town of Llandudno, is the reigning Welsh U17 champion at 67kg.
Seamus has been weightlifting for five-and-a-half years, and described his third place in Leeds as his biggest achievement yet.
“This has been the third British competition I have been in, and in each competition I have improved,” said Seamus, who is studying Level 3 Sports Coaching, Development and Fitness at Coleg Llandrillo’s Rhos-on-Sea campus.
“It was one of the hardest competitions I have been in because I was competing against two professional athletes who represent Great Britain.
“It gave me a chance to prove to people what I am capable of doing in this sport. It was a massive experience and was by far the best experience I have had in the competition, with the people I was competing against and also being able to compare myself to the people my age and my weight, and see where I could go with the sport if I carry on training hard.”
Seamus thanked his coach Nia Roberts for her support, as well as the staff and students at Coleg Llandrillo, saying: “I wouldn't have been able to get into this competition and have this opportunity without coach Nia.
“College has supported me a lot with weightlifting. Having access to the gym means if I’m not able to make training after college I’m able to do it during the day.
“All the tutors have been very supportive, supporting me in all the competitions and wishing me luck. Also all the students have been helping me to stick to my training and my diet!”
Matthew Morris, Level 3 Sports Coaching, Development and Fitness Course Coordinator, said: “Seamus has recently progressed on to Level 3 Sports Coaching, Development after completing his Level 2 Sport (Performance and Excellence) course.
“Seamus is a hardworking, dedicated and talented individual who is a pleasure to have in the classroom.
“He is excelling in his studies and is implementing the knowledge he is learning in modules such as Anatomy and Physiology and Fitness Training for Health, Sport and Wellbeing into practice.
“His third place in the British Championships is a fantastic achievement and we wish him well in future competitions."
There are still places available on the Level 3 Sports Coaching, Development and Fitness course at Coleg Llandrillo in Rhos-on-Sea. For more information, including how to apply, click here.