Lisa Mckenzie on the day she was arrested

They say you should never read below the line after you publish an article in the public domain. Yes, but what if you’re a sociologist? You have to read the comments – it’s your job to know how society reacts to a particular viewpoint. Besides, one of a sociologist’s prime traits is extreme nosiness. So I look. My favourite comment came after I had written in a national newspaper about being a working-class academic and living on a council estate: “Where is her child’s father?” a reader demanded. That was just class – in every sense of the word.

I have written and published several articles that are aimed at the general public rather than academics. I am, after all, a public sociologist. I have written a book, Getting By: Estates, Class and Culture in Austerity Britain, which I am proud of; it is free of sociological jargon and relatively cheap to buy. I am also an activist, and I have used the knowledge, the platform and the confidence that academia provides to fight inequality, and to shout (very loudly) about the consequences for the poorest in society of the cruel intentions of neoliberal governments (among which I include New Labour, whose social exclusion agenda was similar in language to the Conservatives’ “Broken Britain” rhetoric and was just as demeaning to working-class people).

Being a working-class academic, I know – and I mean I really know – what the impact of neoliberal policies is on poor communities; I know the unfairness of class inequality and how crushing poverty can be for a family and a community. So I speak about it, I write about it and I act upon it. And whenever I’ve done so, my public profile has risen. But this is a good thing for a public sociologist, isn’t it?

Well, on one recent occasion, when I acted on my disgust at a particularly nasty and vindictive piece of housing policy in London, it seemed my rising profile was a bit too much for the Metropolitan Police.

On 2 April, I was in Chingford, whose incumbent MP, Iain Duncan Smith, was campaigning in the 2015 general election. And I was campaigning there, too: I was standing against the former Tory leader – and architect of the party’s attacks on welfare – for Class War, a radical Left political party that was described by Guardian columnist Polly Toynbee as “a group of photogenic fruitcakes”. I am not interested in becoming an MP; it’s not my sort of direct political action. But I am interested in challenging the status quo, disrupting the system, and pissing off the Establishment. I’m interested in pushing boundaries, and finding out just how far a very working-class and proud woman can get.

I had some media interest that day in Chingford, and there was a Guardian photographer with us. After having a few drinks in the local with some Chingfordians who proudly told me that they hated Sir Winston Churchill and would definitely vote for me, I headed back to the East End, to One Commercial Street, a “landmark” new 21-storey block of flats on the boundary of the City of London and Whitechapel. I was attending Class War’s weekly picket of the building, which was in its 26th week.

One Commercial Street is one of London’s many new multimillion-pound housing developments that, in order to get planning permission, have been required to include a small number of “affordable” flats. The growing trend for these upmarket developments is to segregate the less well-off tenants from the wealthy homeowners by forcing them to use separate entrances, or “poor doors”. And it’s not just doors: even their bicycle storage spaces, rubbish disposal facilities and postal deliveries are separated, too. When I first heard about this development, I immediately knew that it was wrong. I certainly didn’t need to carefully weigh up whether devaluing a person and making them walk round the back was better than providing no home at all – which is the argument most often levelled at the protest.

Our weekly picket always started at 6pm on a Thursday and always ended at 7pm – we are very punctual anarchists. After 45 minutes of a very uneventful picket, I was surrounded by about 10 police officers, and “snatched” – a tactic the Met uses to remove a person from a crowd. I was surrounded, my hands were cuffed behind my back and I was forced into a van. I was being arrested, they informed me, for an alleged offence that had happened two weeks previously. My charge was criminal damage: I had allegedly placed a sticker on the window of One Commercial Street, which had required the window to be cleaned at a cost of £50. I was taken to Bethnal Green Police Station, kept in handcuffs for two hours and held in a cell until 1.30am. That said, it wasn’t all bad: a well-meaning copper thought that I might need a book to read (me being a doctor) and gave me the comedian Frankie Boyle’s autobiography, My Shit Life So Far. The dedication on the first page says: “To all my enemies, I will destroy you.” That page now takes pride of place on my fridge door.

Almost two months later, further charges were added when I surrendered for bail at Bethnal Green. These were so-called Section 4A and 5 public order offences, according to which you can be imprisoned for using “threatening [or abusive] words or behaviour, or disorderly behaviour” or for displaying “any writing, sign or other visible representation which is threatening [or abusive], within the hearing or sight of a person likely to be caused harassment, alarm or distress thereby”. My offence was to have held up a poster depicting the graveyard from the film of Oh! What a Lovely War with the words “we have found new homes for the rich” on it. If I had been found guilty, the Crown Prosecution Service and the police would have applied for a Criminal Behaviour Order (the “new Asbo”), which would have curbed my freedom of speech and movement by stipulating in law places that I was not allowed to go and people or groups with whom I was not allowed to socialise.

Four days before my trial, the CPS accepted that there was no evidence that I had caused or committed any offence. You might have expected its response to be to drop the case, or to offer no evidence. No: instead, it added the charge of “joint enterprise”, a 300-year-old offence that has been revived in recent years to allow the police to charge someone with another person’s crime if they can be demonstrated to have shared a purpose with them, whether they were present at the scene of the crime or not.

I first came across joint enterprise when I was undertaking research in my community in Nottingham after the August 2011 riots. A group of young black and mixed-race men were charged, found guilty and imprisoned for being on a street where criminal damage was caused on a particular night, even though both the police and the CPS accepted that they had no links to each other. I became very close to the mother of one of those young men, who ended up being imprisoned for three years. My heart went out to her; I knew her son could easily have been my son. During those four days of rioting across England, if you were a young black man from particular neighbourhoods, you could not be on the streets – you could be arrested and imprisoned for who you were, rather than for anything you had done. I wrote about this in Getting By, and I have stayed close to mothers and sons whose lives have been wrecked by joint enterprise, and by lazy, classist and racist policing.

The charges against me meant that I was tried in a magistrate’s court, at taxpayers’ expense. It would also have left me personally out of pocket if I had not successfully crowd-funded my defence costs; in the past five years, Legal Aid has been slashed for all kinds of offences, including not putting a sticker on a window while someone else – a “person unknown in a mask”, according to the police – did.

On 21 October, I was found not guilty of all charges. Under questioning, one of the police officers, a prosecution witness, admitted that I had been “profiled” from CCTV and photographs of the protest: the police had actively investigated who I was despite my having committed no crime. The district judge, in his closing statement, said that he felt “very uncomfortable” with the fact that I had been subject to such treatment. It seems that being a public sociologist can have wider and more worrying consequences than the venom of Daily Mail readers writing below the line.

I was worried that I would be judged for being involved in Class War: people react strangely to that term. But I was wrong. Many individuals and groups, including from the academic world, have rallied around me, not only in relation to my case but also regarding the issues that it throws up. Rising inequality in the UK means that class politics are once again becoming central to our understanding of oppression: something attested to by the fact that my crowd-funding campaign reached its targeted amount within 24 hours.

Our freedom as academics to disagree and to offend the status quo is at risk from the police, from government and from university management. Ideas are the most dangerous tools in any revolution, and, as academics, thinkers and activists, we cannot take our freedom to explore and promulgate them for granted. That freedom has been hard won and will continue to be challenged by those who are afraid of us.

Lisa Mckenzie is a research fellow in the department of sociology, London School of Economics.