The family of a much-loved 12-year-old boy from Carmarthenshire have paid an emotional tribute following his sudden death, just days after he reportedly said: “I think it’s my heart, mummy.”

Harrison Angell-Chapman, known affectionately as Harry, passed away on 6 May last year at the family home in Betws, near Ammanford, after suffering a cardiac arrest. His sudden death has left his family and the local community in profound shock.

A popular figure at Ysgol Dyffryn Aman, Harrison was remembered at his funeral with balloons and his favourite basketball, reflecting the joy he brought to those around him. Friends and teachers gathered at the Chapel of Rest at Bwtrimawr, Betws, to celebrate his life.

Harrison’s mother, Sarah Angell, said he had no known underlying health conditions and had never been seriously ill. “He had a severe viral infection in the weeks before, but he hadn’t otherwise been ill,” she recalled.

“The heart isn’t something you think about at that age, is it? We thought we’d be better safe than sorry and booked an appointment, but Harry said he’d improved, so we cancelled it. I was a GP’s receptionist myself and knew how precious appointments were.

“But on the Friday morning, he suddenly said: ‘I think it’s my heart, mummy.’ He wasn’t right that bank holiday weekend, but he wasn’t too bad either. He wasn’t playing his games as usual but was lying on the sofa with a hot water bottle on his shoulder. I remember he came with me to Tesco, and he seemed okay.

“He talked about going back to school on Tuesday after the bank holiday, but about half an hour before he collapsed, he said: ‘I don’t think I can.’ I said, ‘okay,’ and was making arrangements for him to stay with his gran the next day as I needed to go to work.

“He was upstairs in the bathroom and suddenly screamed: ‘Mummy, I’m dizzy.’ As I opened the door, he collapsed to the floor. His eyes had rolled and he wasn’t responsive. He did regain consciousness, but when we got him to the hospital, we realised how serious it was.”

At Glangwili Hospital in Carmarthen, Harrison was found to have an extremely high heart rate and blood pressure. While being prepared for surgery, he began coughing and suffered a cardiac arrest. CPR was administered for eight to nine minutes, reviving him temporarily, but he later experienced a second cardiac arrest and passed away at 9.53pm.

A post-mortem examination provided a provisional medical cause of death as myocarditis – inflammation of the heart muscle – alongside a respiratory tract infection, a rare combination for someone of his age.

“There was nothing they could have really done at that stage,” Sarah said. “They tried. They tried so hard. They kept me and his dad with him the whole time. They allowed me to be with him right until the end. They were amazing.

“When they were taking him into theatre, Harry kept pulling his oxygen mask down and saying to the doctors: ‘Thank you for helping me.’ That was the sort of boy he was. He was such a gentleman. We didn’t know he was dying at the time, and I really hope he didn’t either, but to have a 12-year-old boy thanking the medics like that just breaks my heart.”

Sarah praised the ongoing support from hospital staff, who continue to monitor her daughter’s heart health. “His sister has been unbelievable. She is so determined and resilient and hasn’t stopped revising for her GCSEs. She’s incredible,” she said.

Paying tribute to her son, Sarah said Harrison loved Pokémon, gaming, basketball, cherry blossom trees, and Christmas. She now has two cherry blossom trees in the garden as a remembrance area.

“The whole community has been really shocked by Harry’s loss. I think they’re also worried for their own children.

“Harry was the best. He was insecure in many ways, yet so popular. His friends made him the centre of attention. He was even prom king in Year Six, and he couldn’t believe it. His group of friends, which he had from nursery, are inseparable. They took their own money to buy a bunch of flowers and turned up at our doorstep. They’re a beautiful bunch of kids.

“Harry hadn’t been at secondary school very long, but he was already well-liked. His teachers, who hadn’t known him for long, signed the condolences book with such lovely messages. Many start by noting his infectious smile, which is absolutely right. He always wanted to make people smile.

“I know every mother thinks their child is special, but Harrison was truly wonderful. He had a lovely 12 years, but he should have had so much longer.”

Harrison’s inquest was opened in August and is expected to conclude next year. Sarah said the family hopes it will provide answers about how and why their son died. “Why did it happen? This doesn’t normally happen to children. It is so cruel. We still have no real understanding,” she said.