On December 21, 1988, he looked out of his front door in Rosebank Crescent and saw that the sky was on fire.
He recalls seeing a "brilliant orange ball of fire".
He remembers the intense heat, remembers seeing the vast ball of fire spitting drops that fell towards the earth.
The drops, he learned later, were of kerosene - the ball of fire was the wing of the stricken Pan Am airliner as it hurtled towards Sherwood Crescent.
He found the body of a girl, lying on the pavement at the top of the street.
In the aftermath of the tragedy, Mr Kerr became chairman of a residents' group for the Rosebank and Park Place areas, which opened a much-needed drop-in centre for local people.
He also became part of the Lockerbie Community Liaison Steering group.
In 1989 his community-minded efforts won him the British Empire Medal in the New Year's Honours List.
He's 77 now, but looks younger.
He walks every day - there are lots of opportunities for bracing walks around here.
Mr Kerr was born just across the road from his home in Sherwood Park. Later, he spent three years with the Royal Scots Greys.
Returning to civvy street, he spent 31 years working for the electricity board, working on overhead lines and other jobs, before retiring.
By chance, he was the one who put in the electrics into this house when it was being rebuilt. It, and other houses, were levelled in the 1988 disaster.
He and his wife lived in Rosebank Crescent for 32 years; 14 years ago, they moved to their current home.
The view on to their back garden is peaceful.
There's lots of greenery.
Local wildlife has been spotted here - he once saw a couple of deer, only a few yards away. Foxes, too.
To the left, rising above a clump of trees, you can make out the property at 1 Sherwood Crescent, the only house there left unscathed.
At the time it was occupied by the local parish priest, Patrick Keegans.
Today, on the 25th anniversary of the disaster, he was planning to lay wreaths at Sherwood and three miles away at Tundergarth, where the nose-cone of the Boeing 747 landed.
"The community council has done that every year, for years," he says.
"It's not just on the big anniversaries like this one. We remember every year.
"We always remember the 21st of December, but the rest of the year is ours. It's always been when we get back to normal.
"At my bowling club, after the first anniversary we kept talking about the disaster, day after day after day.
"We never stopped. Then, suddenly, the conversation got back to football, and that was us. When we started getting back to football and other normal things, we knew we had talked the disaster out."
Like many people in Lockerbie, particularly those who were living here in 1988, Mr Kerr has watched the media's never-ending interest in the story, and with commemorating it every five years.
He is not alone in thinking that the town should be allowed to move on.
"I want to see Lockerbie prosper. It has got a great chance of doing that.
"It has a great location. We've got a mainline railway station. We've got the M74 and a relief road. I've noticed more building work coming into Lockerbie now than ever before. There's loads and loads of work. There's the cheese factory, of course. There's a big business north of Lockerbie, started up by a local lad, and it's huge.
"Robinsons builds huge sheds for farmers. There's a chemical factory, there's a cardboard factory.
"They're building more houses here, too, which is what I want to see. The town is busy expanding."
He mentions, too, the recently-unveiled sheep sculptures in the nearby town centre. The sculptures have divided local opinion but it was one of those stories about Lockerbie that at least didn't mention the 1988 disaster.
"It looks nice," he says, "and the kids love it - they jump on the sheep's back and get their photographs taken.
"They've tidied up that whole area there, and it has helped. Every town centre is the same, with empty shops. We've got a number of empty shops here that are being turned into flats.That helps, too."
Mr Kerr says there's a strong community spirit in Lockerbie.
"It's strong, very strong," he said. "I compare it with what happened in Glasgow the other week, when a police helicopter crashed into the Clutha pub.
"If anything happens, people come to help you. Scots people are like that, I think. Always ready to help others. Here, after the disaster, if you asked people to come out and do anything for you, they were there for you. There would be gangs of them, willing to help.
"The Salvation Army here was a terrific help after the disaster. Nothing was too much trouble for them. The church ministers, and Pat Keegans, were great as well."
Twenty-five years ago, the people of Lockerbie saw things that no-one should ever have to see. Ever since, they've had to share their memories with the outside world, especially every five years.
"It's been a long, long process," Mr Kerr says, "but Lockerbie, I think, is finally getting on."