'I held it together until the credits then I saw his name and I just buckled' Stabbed Potter star's dad on seeing son in new film.

Byline: VICTORIA WARD

IT SHOULD have been one of the happiest moments of his life.

But Colin Knox, dad of Harry Potter actor Rob who was stabbed to death in May last year, could only speak yesterday of the agony and overwhelming pride at seeing his son on the big screen.

Tomorrow Rob, who played boy wizard Marcus Belby, should have been joining stars Daniel Radcliffe, Rupert Grint and Emma Watson at the Harry Potter and the Half Blood Prince premiere.

Instead, about 60 family and friends watched an emotional private screening at the weekend to help them come to terms with seeing him in scenes finished just three days before he died at 18.

Colin, 56, still devastated by his death, said: "I held myself together until the credits rolled. But when I saw his name up there, that was it. I buckled. Everyone burst into applause. It was for Robert, as though he'd been waiting for that moment of acclamation."

The talented young actor features in three scenes and Colin said: "We were given an overview and knew roughly when we'd see him on screen.

NERVOUS

"I was very nervous about seeing it and thought I'd just collapse but I didn't until the end, perhaps because I was in awe of him. But there was laughter and tears.

"It allowed the whole family to see it collectively and share our sorrow and our pride. It was a real mixture of both."

Colin, fighting back tears, said: "It's so sad knowing he'll never see it. He was so unbelievably proud to have got the part. He loved every minute of it. And he never got to see the fruits of his labour."

Rob was killed outside a bar in Sidcup, Kent, in May 2008 by knife-wielding thug Karl Bishop, 22. The pair had clashed the previous week and Bishop chillingly warned: "I'm going to come back next week and someone's going to die."

Rob stepped in when Bishop threatened younger brother Jamie, now 18, and was stabbed to death.

But Colin, who said it was surreal to see him alive on the screen, added that one scene in particular moved him: "What I saw was Robert being Robert. His sense of humour comes across. His character is so much like Robert himself, so cheeky and bubbly.

"I don't think his acting would have been too pushed."

He added: "When the film ended, no one moved. There was complete silence. We all sat and watched the credits right to the end - everyone with their own thoughts.

"It was very surreal. I've never watched any Harry Potter films, or read the books.

"And there I was watching it on the big screen, and my son was in it. It was like he shouldn't be there, but when he was he made me laugh."

But it was the praise lavished on the young actor by two of the producers and a director that moved Colin the most. He said: "They told me how professional he was, how they enjoyed working with him and how easily he fitted into the Harry Potter family.

"It was like the first minute on the pitch for a Premiership player and I'm so glad he got to experience it. Even if it was the last moment he was alive."

The teenager, who had also appeared in ITV's The Bill, impressed producers so much they promised his role would be expanded in Harry Potter and the Deathly Hallows. Colin, from Greenhithe, Kent, also treasures three text messages Rob sent him.

PROUD

One of them told how happy and proud he was to be there on set and how much he was enjoying himself.

Colin said: 'I made sure he was a friend as well as my son. We hugged and kissed every time we saw each other and said we loved one another."

Colin will be joined by exwife Sally, 51, and their other son Jamie, on the red carpet for the London premiere, rubbing shoulders with Daniel Radcliffe, 19, and other cast members including Julie Walters, Michael Gambon and Potter author J K Rowling.

But despite his pride, Colin said time hadn't healed his grief: "The only way I can describe it is if you imagine walking along a cliff top holding hands with someone, and you turn round and that hand is suddenly empty.

"I live this nightmare every day. I just want him back."

CAPTION(S):

MEMORY Colin with Rob DEVASTATED Dad Colin & mementoes of his son yesterday MOVIE Rob Knox as wizard Marcus Belby, seated right