Video report from ITV News Meridian reporter Cary Johnston
"Not long after [Andrew] left school, he came to work for me on a roofing business I had at the time," says Andy Ledbury.
Mr Ledbury, who now runs a garden centre in Wallingford, was a family friend of PC Andrew Harper.
"He had always wanted to be a policeman," he says, "and he took a lot of stick because you can imagine on building sites for wanting to be a policeman."
"He said when left to purse his career, he said he would have the last laugh, which focused everyone else once he became a policeman."
Mr Ledbury says moment he heard of the 28-year-old officer's death was "horrendous."
"I had a call from the ex-colleague we worked with when we were roofing, and he had seen it on the news at seven in the morning.
"And as you do, you hope that it isn't Andrew, but the minute they mentioned his local police station that's when we realised that it was Andrew. "
PC Harper had only recently married his childhood sweetheart, Lissie, and should have been spending the end of 2019 on honeymoon in the Maldives.
Mr Ledbury says that Lissie has "been very strong" and that the officer's family have been "touched by all the support they have had."
"You remember his smile, the fact that he was always pleased to see you, good company, good sense of humour, " Mr Ledbury says.
"There were two things we knew he wanted to do at the age of 18.
"One was to marry Lissie, and the other was to be a police officer on traffic.
"He stuck with that all the way through, he never wavered, that's the direction he was going."