I was arrested at the last royal wedding. This time, the police must protect our right to protest.

As we are encouraged to deck our streets with bunting, and as our screens fill with footage of monarchists camping outside Windsor Castle, it’s easy to forget that not everybody is overwhelmed with excitement about Harry and Meghan’s nuptials.

For many, like me, it’s a high-profile chance to peacefully express our belief that the monarchy is outdated, undemocratic, and should be abolished.

Our right to do so is a core part of our democracy. Freedom of expression and the right to protest are essential rights that should be celebrated and protected – especially on a day like Saturday, when the world’s eyes will be on the UK.

It is to be hoped, then, that police have had a rethink since the last royal wedding – Kate and William’s – when their response was so disproportionate and authoritarian that their actions are still facing legal challenges today.

On that day in April 2011, myself and nine friends were kettled, arrested, and detained for half the day. We had committed no crime and had no intention to do so – and police had no evidence to think we had. We were held because we were republicans and we wanted to protest. Ours were among dozens of apparently pre-emptive arrests that took place around the last royal wedding.

We had gone to Trafalgar Square that morning because we had seen an event on Facebook announcing a republican protest. When we arrived, the massive numbers of both police and private security – as well as the sheer volume of people in the square – made it clear that holding any kind of protest would be impossible.

Whoever had organised the Facebook event had obviously reached the same conclusions as there was no sign of any republican presence. We decided to go instead to the street party in Red Lion Square, Holborn, organised by the pressure group Republic.

Kettled

While we were waiting outside Charing Cross station for another friend to return from the shop, British Transport Police (BTP) officers became interested in who we were and what we were doing there.

They searched us under Section 60 of the Criminal Justice and Public Order Act – which lets officers search people with no suspicion – and found homemade placards and a megaphone. As they searched us, one officer said: “the Met have been going round, rounding up people before the wedding, to make sure there’s no problems”.

We’d heard about the squat raids that had taken place the night before. The officer’s comment confirmed our suspicions that the police were using pre-emptive arrests to keep republican voices off the streets.

The BTP said the Metropolitan Police also wanted to speak to us, so we were detained until a group of more than 20 officers, including members of the Territorial Support Group, arrived and placed us in a “kettle”. After some time, they moved in and arrested us. We were told we were being arrested to “prevent a breach of the peace”.

We were held in handcuffs, without being told where we would be taken and if we would be charged, until we were marched onto an unmarked, civilian coach and driven to Sutton police station in South London.

Only four of us were booked into cells. The rest were held – still handcuffed – in the station yard. Eventually a senior police officer emerged to tell us they had decided the threat had passed and we were free to go.

We believe what happened to us was unlawful. The police’s common law powers let them make arrests in cases where a breach of the peace is “imminent”. Nothing we did or said, or anything in our behaviour, could possibly have given them reason to believe this was the case.

Political arrest

We were arrested because of our political opinions and the police’s belief that we might do something which might cause a breach of the peace at some point in the future.

The implication of our arrest was that, on 29 April 2011, it was illegal to be a republican within a designated area. What happened to us, and other royal wedding “precrime” arrestees, has dangerous implications for democracy and civil liberties in Britain. The state cannot be allowed to attack freedom of thought and expression in this way.

Our legal appeal against our arrests is ongoing, but we hope the fact we’ve pursued it will make Thames Valley Police think twice before taking a similarly authoritarian attitude to dissenters in Windsor. Liberty has been consulting with police to urge them to take a more respectful approach. Anyone who feels their rights have been breached on the day can contact their free advice and information service.

The debate on whether the monarchy’s continued existence is compatible with meaningful democracy must be had. Whatever your view, the use of state force to intimidate, silence dissent, and detain potential protesters is an affront to democracy and civil liberty.

Hopefully the police have learnt lessons. The world will be watching.