Three years ago,  Hattie Deards and her husband Tom lost their baby son Theo to cot death. Theo was just 12 weeks old when he passed away suddenly on the 30th of December, 2012 on what was an otherwise ordinary Sunday for the Deards family and their three young children – Ned, Esther and Theo – who had spent the morning together at the park.

An open letter to the son I lost to cot death, three Christmases ago https://t.co/Bp0v3Vkkrs pic.twitter.com/aw0sWMAMlS

It was, Hattie recounts, “a milestone day” as baby Theo had just reached 12 weeks old. In a heartbreaking piece written for The Telegraph, Hattie has penned a devastating letter to the son she lost too soon depicting the anguish of that harrowing December day.

“I was starting to feel more normal, the exhaustion of the early weeks subsiding,” Hattie wrote. Theo, a “dream baby” had spent the morning at the park with his parents and siblings. On the ride home, Hattie held his hand as he stared up at her. On that final drive home, Theo fell asleep with a smile on his face and Hattie took him upstairs to put him to sleep in his cot.

Hattie called an ambulance, and their family home and quiet street was quickly filled with people. The older children were taken to the neighbours as Tom performed CPR on baby Theo until the paramedics arrived.

Fifty-five minutes after Hattie had found Theo lifeless in his cot the paramedics managed to restart his tiny heart.

Theo was taken to West Middlesex Hospital with his Dad when two policemen arrived at the Deards’ family home to escort Hattie to the hospital quickly to see her baby boy.

It is then that doctors tell Hattie that Theo’s heart stopped again once he arrived at the hospital, and that he is now being kept alive with life-support machines.

Theo was then transferred to the Great Ormond Street Hospital for more detailed brain scans and Hattie and Tom were put up in a room opposite the hospital overnight.

“Hours passed in agony, thrashing around, walking the corridors and watching the darkness of Queens Square from the window, feeling my breasts fill up with milk and with no baby to feed,” Hattie wrote.

The next morning the Deards arrived at Theo’s bedside where their young son’s skin was turning yellow as his organs began to fail.

“We never fought to keep you alive on the machines,” Hattie wrote. “But I was terrified when the time came.”

Hattie and Tom were in a private room with their baby boy when he passed away. Ten months later, they welcomed another baby boy.

Since their heartbreaking loss, Hattie and Tom have raised over £5,000 in Theo’s name to support The Lullaby Trust.