When eight-year-old Sam Starr was going through his second round of treatment for acute lymphoblastic leukaemia, Camp Simcha appointed then volunteer Hayley Phillips as his "big sister". Sixteen years on, Ms Phillips was the first name on the list for a party to celebrate his graduation from Leeds University, where he achieved an integrated master's degree in maths.
It is an example of the bonds formed between the children with serious illness supported by the charity and their Camp Simcha big brother or sister, who are aged between 18 and 25 and trained to be a special friend. Well over 200 are on call.
Ms Phillips, who now works for Camp Simcha as retreats co-ordinator, recalled that "we had lots of fun together, despite what Sam was going through. We have stayed in each other's lives ever since, long after my role as big sister officially ended. You become close to a family at a very stressful and frightening time in their lives.
"Watching Sam come out the other side of that and then grow up to be such a fine young man is very special."
Mr Starr, 24, from Chelmsford, said that he had immediately got on with his Camp Simcha sister. "When you are sick or in hospital and surrounded by family members who are worried and also suffering, it's really uplifting to have someone outside of it to come in to keep you company. Hayley made me feel better because we would talk about different things and she'd bring a different perspective to my daily life. She was also someone I felt I could confide in when I needed to. It's hard to talk to your family when you are feeling really low because you feel guilty about upsetting them but I could tell Hayley about things.
"She also really helped me with the school work. I had loads to do - not just homework but all the stuff I had missed by being off school. It was quite lonely and isolating doing it on my own, but Hayley would come to the hospital and work through it with me."
His mother, Jo, added that "at one point Sam was having lumbar punctures every month but he hated having a general anaesthetic. He used to insist on being awake for them, even though that was not standard practice at his age. He wouldn't let me be in the room because he knew it was hard for me to see him in pain, so Hayley sat with him every time talking to him while they did it."
He finished his treatment two years later and has since been in remission.
Camp Simcha chief executive, Neville Goldschneider, said: "Our big brothers and sisters play a huge part in the lives of the children we support, bringing a ray of sunshine in dark times. It's wonderful when they - and we - get to see those children return to good health.
"If the worst happens and a child we are supporting dies, Camp Simcha is still there to help the family while they need us. This applies to the big brothers and sisters and also to the family liaison officers and other relevant services. Initially there would be a crisis support set-up and then ongoing support."