Until recently, the Hong Kong government had a working relationship with the Professional Teachers’ Union. It has long been part of the traditional opposition that was even tolerated by Beijing.

But, as local politics became radicalised and protests turned violent, the union increasingly neglected its original mandates, which aimed to look after teachers’ welfare and also to push gradually for greater democratisation in the city.

As radical localism morphed into the anti-government/anti-Chinese movement and turned away from the old-style pan-democratic mode of moderate politics, mainstream pan-dems such as the union’s chief, Ip Kin-yuen, found themselves at a crossroads.

Those like Ip declared they didn’t support radical politics such as the call for Hong Kong independence, yet managed to consistently express support for those who did, such as the younger localist leaders from the student unions of local public universities.

From the Occupy protests of 2014 to the riots of 2019, the union was at the forefront of the protests and served as a fierce critic of the police and the government. Throughout the violent months in the latter half of 2019, it never once criticised the violent protesters, rioters and arsonists, but repeatedly rounded on officials. It even called on teachers to rally and students to boycott classes.

For Beijing, that was the last straw. It might have tolerated the union’s long-standing pan-democratic politics and even its transformation into a de facto political organisation, but feeding anti-government politics to young children in schools was unacceptable.

The fact that China’s state media called for a crackdown on the union and that the local government promptly followed the diktat last week was not in itself surprising. The real surprise was that it had survived for so long.

With 95,000 teachers and other education workers, the union has always had enough clout to put its chief in the functional constituency seat for education in the Legislative Council.

Indeed, for more than two decades, it had been one of the most reliable seats for the pan-democratic bloc in Legco. Ip himself was the last lawmaker for the education sector.

But since the local government has now severed all ties, the union will no longer be able to send its own candidate to contest the seat.

It didn’t have to be this way. Its late founder, Szeto Wah, was a great pan-democrat and also a great Chinese patriot who was respected by Beijing. Sadly, his followers didn’t follow his vision.