Sometimes, after a few drinks and with only a keyboard for company, he will indulge in one of the rants on social media that he describes as “my meltdowns”.

Then his mates - many of whom, like him, suffer from Post-Traumatic Stress Disorder - will reach out to check that he is letting off steam and hasn’t blown a gasket.

There is no way Ian “Dizzy” Harris could have known that what began as a routine stolen car check would end in a fatal confrontation with one of Australia’s most notorious gunmen.

Nor could he have known that those critical moments where he took a life and nearly lost his own would leave mental scars that would change his very character and cost him the career he loved.

Harris and the man he had to kill, Edward James “Jockey” Smith, had one thing in common – they both loved their respective careers.

Born in 1942 as the second of eight children, Smith was an apprentice jockey but by the time he left his teens he had found his true calling - crime. He became a prodigious armed robber, a master prison escapee and a crook prepared to use a gun to avoid arrest.

He twice tried to shoot police only to fail, once because a policeman was quick enough to place his thumb between the trigger and the breech and the second time when St Kilda policeman Russell Cook was searching a car and Smith pulled the trigger to shoot him in the back but the gun jammed.

He also threatened to shoot a store detective and in 1976 shot and wounded Constable Jerry Ambrose in Sydney.

Harris, who was brought up in Melbourne, had a cousin in the Dog Squad and by the age of 14 planned to become a policeman, joining three years later as a cadet. He graduated in 1980, worked in a series of busy stations, transferring to Ballarat in 1991 where he met his wife Jacinta (they would raise two sons). He had a reputation as a reliable cop who maintained a sense of fun - an asset in any station.

In December 1992 he was assigned to relieve at the nearby town of Creswick, where the resident sergeant was sick and the senior constable, Russell Cook - the same policeman Jockey Smith had tried to shoot nearly 20 years earlier - was on leave.

For Harris, 31, working solo in Creswick was no issue: it was a quiet community with the occasional family dispute, rowdy party or disturbance at the caravan park. In two weeks relieving he had not made a single arrest.

The afternoon shift on Saturday, December 5, looked like any other – he would check the three local pubs, answer calls for help and cruise on patrol until knock-off time.

What Harris - along with all the regional police in the area - didn’t know was that not far up the road was a massive crime department operation aimed at arresting a team of professional armed robbers.

The target was the notorious Christopher Dean Binse, who had escaped from Parramatta Prison six weeks earlier and then robbed the Commonwealth Bank's Doncaster branch of $160,000.

Detective Sergeant Steve (Larry) Curnow had been tipped off that Binse and two others, one a big name from Sydney, planned to rob an Armaguard truck in Melbourne. They were also rumoured to be planning to use knockout gas to disable bank staff at a north suburban branch.

The squad launched a secret operation, code-named Farnsy, and found Binse had turned a rented hobby farm near Daylesford into a safe house. Listening devices picked up that one of the men at the farm was known as Tom. They didn’t know Tom was "Tom Collins", the alias Jockey Smith had chosen for himself.

And so when Tom drove from the farm in a white Ford panel van police decided to let him go, believing he would return and because they didn’t want to alert Binse, who remained the ultimate prize.

Almost certainly if police had known that Tom was Jockey Smith, the heavily armed Special Operations Group would have grabbed him. Instead it was left to one country copper – aided by a local bloke who, acting on instinct, proved to be recklessly brave.

Harris spotted the van on the Midlands Highway travelling at 80 km/h in a 100 zone. His instincts, honed from his stint in the traffic branch, told him that the driver was drunk or dangerously fatigued. He radioed the emergency communications center, known as D24, in Ballarat with the vehicle’s details and was told the van was stolen.

‘‘I followed it because I didn’t want to pull it up in the bush,’’ he recalls.

Eventually the unknown driver stopped next to the bottle shop at the Farmers Arms Hotel. Harris pulled up and tooted the horn to get the suspect’s attention.

As Smith opened the driver’s door Harris saw keys in the ignition, which made him think the stolen van may  already have been recovered and returned to its legitimate owner.

When Harris asked the driver for identification, Smith went back to the car. ‘‘He came back with a car manual in front of him [which he used to hide his five-shot .38 Taurus revolver]. He pointed the gun at me and said ‘Put your hands up, don’t go for your gun, don’t go for your gun’.

‘‘He kept reaching for my gun [holstered behind Harris' right hip] as I backed away to the rear of the car,’’ Harris recalls.

Meanwhile local man Darren Neil, fresh from a day’s prospecting and a few beers, changed his plan to pull into the pub to grab some stubbies when he saw the police car. Concerned he may be over the limit, he decided to drive on - that is until he saw Jockey Smith point a gun at the policeman’s head. He drove back, leaving his two sons in the car, calmly walked over and pushed Smith in the chest, telling him to ‘‘settle down.’’

Having fired a warning shot, Smith now took fresh aim at Harris. ‘‘He said, ‘I’m going to kill you'.’’

But Neil was far from finished - having dropped his kids inside the pub, he jumped back in his car and drove straight at the gunman, stopping just short of pinning him against the police car. This gave Harris the chance to draw his gun and fire three shots from the hip, hitting Smith twice in the body. Fatally wounded, Smith stumbled a few steps before collapsing.

Once the scene was secured, Harris went to the station and made his own recording of events. Eventually he was interviewed by Homicide detectives and at 5am returned to the Ballarat station to hand over his shirt for forensic examination.

By 7am he was at home cracking his first drink. Eventually 15 police joined him and when the police psychologist arrived at 3pm, he had passed out in an armchair from fatigue, booze and emotional exhaustion.

The next few days were a blur. There was a cup of tea with the acting chief commissioner - who presented him with a paperweight - time off, a gradual return to work and nine months later he was back on the road.

But things were different. ‘‘I became very aware [of risk] and was reckless.’’

Harris was involved in three car chases, crashed two police cars and eventually a senior sergeant saw the danger signs, suggesting he take a break from the sharp end of policing.

Despite psychological help, completing a PTSD treatment course at the Austin Hospital, he remained hyper-vigilant, required prescription sleeping tablets and was not in a fit state for general policing. He worked as a court orderly, in the property office, at D24 and the custody centre, where a confrontation with a drug offender proved a tipping point.

In 2008 his doctor told him: ‘‘Ian, that’s it, you’ve had it.’’

As we sit and talk in the front room of his small family home in Ballarat, Ian rifles through a cardboard fruit box that holds articles from that night in Creswick. In front of him are a dozen books, including one by this reporter, that examined the shooting with various degrees of accuracy.

Without exception they concentrate on the notorious crook prepared to shoot to escape, not the policeman who had to shoot to survive.

Ian says that when he resigned, senior police told him they would assist his retraining for another job. ‘‘That didn’t happen,’’ he says, without bitterness.

He also believes an offender who was likely to be armed should not have been allowed to drive from a farmhouse ringed by armed police, detectives and surveillance officers. ‘‘He should have been stopped in Glenlyon, not by me in Creswick.’’

The negative influence of social media - the trolls, the bullying, the lies and the keyboard warriors - is often the subject of scrutiny. But for Ian, social media keeps him in contact with a loose collective of retired police from around the world who have developed their own peer support network.

‘‘As PTSD sufferers we have learned to look after each other,’’ he says.