According to my former colleagues, history teachers in an urban English state school, anyone who votes for the Conservative party is ‘thick’, the British Empire was ‘unambiguously evil’ and capitalism leads to ‘mass inequality and misery for the vast majority of working people’. The only answer was, you guessed it, socialism. Yes, the cliché of the Little Red Book-carrying schoolteacher is alive and well.

As the only right-of-centre teacher in the history department, I found lunchtime particularly galling. My colleagues would sit around denouncing the British empire, Michael Gove’s changes to the national curriculum and the government’s ‘ideologically driven’ attempts to cut the nation’s deficit. But what worried me more was their willingness to indoctrinate their pupils with the same world-view. On one occasion, I overheard three of them discussing the delivery of a unit provocatively titled ‘Should we be proud of the British empire?’ As you can probably imagine, there was one answer they considered right: ‘No! We should be ashamed. Look at Amritsar, what we did to the Native American Indians and our involvement in the Middle East,’ said one, shaking his head.

In history class, pupils discussed a litany of British atrocities, from forcing widespread opium addiction upon a benighted, infantilised Chinese population to massacres in India and Africa and ethnic cleansing in North America and Australia. There was only one task asking pupils to consider the question: ‘How did the British Empire improve lives?’ and this was homework. There was no classroom discussion about the spread of capitalism, parliamentary democracy and the rule of law; the propagation of ideas, literature, technological and medical advances; or even the abolition of the slave trade.

Mostly, on this subject, I held my tongue. I was a supply teacher on a zero-hours contract and was worried about being sacked.

If only I had stuck to this resolution. After keeping schtum for two months, I finally challenged a colleague’s view of the Tories. ‘Why are Tory voters thick?’ I asked. ‘Is it just because they happen to disagree with you?’

‘No,’ he replied. ‘Because they voted for cuts’.

‘Perhaps they saw the cuts as necessary,’ I said. ‘Surely it’s better to make savings now, rather than keep spending money we don’t have, go bankrupt and, like the Labour government of 1976, be forced to make even deeper cuts after going cap in hand to the IMF.’

‘That’s rubbish!’ said another colleague. And so it continued, though no one actually raised their voices, until they brushed off my argument with a blasé ‘yeah, yeah, yeah’ before gesturing towards the office door as if dismissing a recalcitrant child.

Two days later, I defended the new national curriculum and the government’s commitment to traditional teaching methods against the head of department’s venomous and sustained criticism.

I said, we do too much for the children we teach; we should give them more responsibility and more freedom to think independently. She said: ‘I don’t want to talk to you any more!’ Before leaving — I had to go to my lesson — I asked why she was being so rude. ‘It’s only a debate,’ I said. ‘Isn’t it a good idea to listen to the views of others, even if you find them hard to stomach?’

My answer came on Friday — two days later. I was called into the head’s office and told that, after a complaint from colleagues in my department, the school would no longer require my services. So I was effectively being dismissed for holding the wrong views, though of course the head dressed it up in a different garb: it was my manner rather than my opinions. Apparently I was ‘too assertive’.

As I remember it, my interlocutors were both red-faced and angry, and more than willing to use inflammatory language. I was told, at one point, that I was unfit to teach.

Interestingly, the head of department who refused to work with me — effectively calling for my dismissal — had several weeks previously decried the cruelty of zero-hours contracts. Where was her left-wing compassion when it came to sacking me, a married man with two children to support?

I suppose I’ve only got myself to blame. For a brief moment, I deluded myself into believing that schools actually encouraged tolerance and the questioning of orthodoxies through intellectual exploration, freedom of thought and speech. How silly of me.