EARLIER this week I inadvertently broke one of the golden rules of journalism: never become the story.

Unfortunately, it was not for a reason I would have chosen - I didn’t win a record jackpot in the lottery.

Instead, it was because of the deeply inappropriate behaviour of a police officer in a position of authority.

Studying for journalism qualifications, you learn about when and where you can legally film, people’s right of privacy, and how that interconnects with others’ rights to freedom of expression.

You also learn the basics of what the police can and can’t ask you to do.

READ MORE: Trade union to confront Police Scotland after National journalist arrest threat

But you don’t need any special training to know that a policeman aggressively grabbing you from behind and saying “let’s get a selfie big man” is not appropriate behaviour.

The officer had done himself no favours by making two things clear before doing that: One, he stated we were on a public street; and two, he already knew I was a journalist.

You could add a third to the list: He knew I was recording.

The video of the incident has since been viewed hundreds of thousands of times and led an MSP to write to the Chief Constable. And it never had to happen.

I had been standing with my bike around 100 metres from the site of a protest targeting the Thales arms company’s site in Govan, which I had gone to report on for this paper.

Demonstrators had blockaded the site since 5am in an effort to prevent it functioning to mark May 15 – Nakba Day.

I’d also reported on a very similar protest at the BAE Systems site essentially next door just two weeks before, and that had been peaceful and uneventful. It looked at 9.30am as if the Thales protest was set to go the same way. So, I thought I’d take one last look around before heading into the office.

READ MORE: Arrests after dramatic clashes between police and protesters at Scottish arms site

However, doing something innocuous on my phone up the road from the Thales site (I think I’d been checking Google maps for the best route to leave by), I attracted the attention of an officer.

When I saw him approaching me, at speed and from a distance, my first thought was that there were some protesters behind me causing a ruckus. But there was no one else around.

When I realised the officer was approaching me, I began filming. To paraphrase The National columnist and legal expert Andrew Tickell, the video that resulted sees the police officer get just about everything wrong. That comment also seems to sum up the public consensus.

Honestly, I have been surprised by the outpouring of support since we published a (blurred due to legal advice) video of the incident on social media and ran a news story.

Even people who are normally fiercely opposed to The National were criticising the police officer’s handling of the situation, and it has led to interventions from both our trade union and an MSP.

The irony of it all is, I was genuinely leaving. If the officer had done nothing, I would have been gone in two minutes.

Instead, his aggression suggested to me that something was up, so I stuck around.

Sure enough, 35 minutes later (I initially said 20 but have since rechecked video timestamps) the police moved in on protesters and clashes erupted.

The heavy-handed and occasionally violent interactions that followed over the next roughly two hours seemed to me to flow from the behaviour of the police.

This behaviour was typified by the officer who manhandled me – while the protest was still entirely peaceful.

Now, as a result of their own actions, the narrative from the event is not the one the police would have liked to project.

Instead of hard-working officers getting credit for doing their duty well and keeping the peace – as had happened just two weeks earlier at the BAE Systems protest – we have questions being asked of the force.

What has happened to the concept of policing by consent? What measures do the police have in place to protect protesters’ and journalists’ right to freedom of expression? Have their officers been trained in even the basics of the law?

Police Scotland will now have to answer these questions and, in my eyes, it is clear who is to blame.