The father of a teenager who was stabbed to death at a party has vowed to make it his life’s work to fight knife crime.

Charlie Cosser was rushed to the Royal Sussex County Hospital in Brighton after being attacked with a knife at an end-of-term party in the village of Warnham, near Horsham, on July 25.

Despite the tireless efforts of critical care staff, 16-year-old Charlie died from his injuries two days later.

Speaking on a visit to the hospital a few months after his son’s death, Martin Cosser said he whispered in Charlie’s ear “the most important promise I’ve ever made in my life”.

He said: “I promised him I would make it my life’s work to talk in schools and to young people about the devastating impact of knife crime on families.

“Charlie wasn’t in a gang, he wasn’t a fighter. He didn’t even like raised voices. If this can happen to him, it can happen to anyone.”

Martin said that he plans to start a charity, Think Twice, in memory of Charlie to raise awareness of knife crime.

As a thank you for their outstanding care, Charlie’s parents Martin and Tara, along with his younger sister Eloise, returned to the hospital to meet with staff and present a £5,000 donation to the critical care team in person.

The Argus: Charlie's family, Martin and Tara, and sister Eloise, with staff at the Royal Sussex County HospitalCharlie's family, Martin and Tara, and sister Eloise, with staff at the Royal Sussex County Hospital (Image: University Hospitals Sussex NHS Foundation Trust)

Martin Cosser told staff: “Words cannot express our gratitude for the dedication and care you gave to Charlie during his time in hospital.

“We had nothing but support and compassion from you and your colleagues. I cannot tell you what that means to us.

“To have to walk into a room and tell our family that Charlie wasn’t going to survive is a very difficult thing to do, but you did that with the utmost care and we will always be grateful for that.

“While he may no longer be with us, Charlie’s memory lives on through the love and support we received from the incredible staff here.

“We hope that this donation will make a difference in the lives of others and serve as a tribute to our son’s memory.”

Tara added: “You never left him alone for one second and you gave him a fighting chance - thank you.”

READ MORE: 'It’s not just him, we're all guilty' - Father of teen murderer speaks out

The donation will help to ensure that other patients and their families receive the same level of care during the most challenging moments.

Charlie’s friends have also raised more than £30,000 for Lives Not Knives, a charity dedicated to preventing youth violence in London.

Staff at the hospital expressed their profound gratitude for the generosity of the Cosser family.

Clare Hebditch, head of nursing for critical care, said: “This amazing gesture of thanks means the world to the critical care team.

“To know that Charlie’s family wanted to come back to the hospital, to not only thank us, but to donate to our trust’s dedicated charity, means an awful lot.

“To hear that our care made a difference is uplifting for the whole team who were deeply affected by Charlie’s passing.

“This donation will now go to support the patient experience in the critical care unit.”