He remembers sending off a player for trying to punch an opponent; he remembers a searing pain above his right ear as he turned his back and walked away. And he remembers waking up in hospital 10 days later.
He has no recollection of the operation to remove a blood clot from his brain after his skull was fractured, or of being moved to a specialist neurological hospital where surgeons fought to save his life.
"I remember falling on to the pitch and being in pain, and I think I remember the ambulance coming, but the next thing I saw was my girlfriend, Jackie, and she told me I had been in a coma for 10 days," he says.
Kelly, 29, was attacked in October 1993 during a game in Bexley, Kent by Timothy Farnham, 30. Farnham, who was later jailed for nine months, waited until Kelly's back was turned before punching him.
"When I came out of the coma, the police asked whether I wanted to press charges. Farnham had said he was genuinely sorry because his father was a referee," says Kelly. "But I wanted to see him in court. In three seasons of refereeing I'd been assaulted three times. I had begun to think it inevitable that someone would be badly hurt or killed. He had to be prosecuted in order to deter others."
The attack has had a profound effect on Kelly. It took place on a Saturday, two days before he was to start a new job as a pub manager. The offer was subsequently withdrawn.
"I get violent headaches every day and suffer from pains in my legs," he says. "Until last April, I was having regular black-outs. After one I woke up needing stitches in a hand wound. I'm still not right, but I'm anxious to get work now. I think it would help.
"My girlfriend and family and the Referees' Association have got me through this, but the Football Association won't even admit there is a problem. Referees are being threatened and abused all the time. They won't put up with it for much longer."Reuse content