Tyrannical regimes seek to control what their populations read, see and hear, lest the people obtain information that might encourage them to question the power that subjugates them. Some go to extraordinary lengths, reaching far outside their borders, to prevent that happening.

One obvious example was the murder of journalist Jamal Khashoggi in Saudi Arabia’s consulate in Turkey last October. A single, bloody act, it made headlines around the world. As it should have.

By contrast, sadly, too little attention has been paid to an insidious long-run campaign of persecution by the Iranian authorities against the staff of the BBC Persian service. It is marked by cowardice and a lack of humanity.

Concerned at the lack of publicity about the situation, the BBC recently staged a special press conference chaired by its world affairs editor, John Simpson. It highlighted what its lawyers regard as “an unprecedented collective targeting and punishment of journalists”. Result? Few, if any, headlines in mainstream media.

Doubtless that failure to heed what Simpson called Iran’s “contemptible behaviour” did not go unnoticed by the tyrants in Tehran. So, they will take heart from that and their under-reported attempts to silence BBC Persian will continue and, possibly, escalate.

As they stand, the facts are shocking. Unable to get their hands on BBC Persian’s London-based staff, Iran’s police intimidate their relatives inside Iran. They freeze their assets, which has the effect of preventing them buying and selling property. They confiscate passports, which denies them a chance to travel. They arrest them arbitrarily, interrogating them for hours at a time and often detaining them for days in prison.

According to an internal survey completed by 96 BBC Persian staff, 45 reported that their parents had been questioned by the authorities and 40 said the same had happened to their brothers or sisters.

Government-affiliated media in Iran have published photographs of London staff, calling them “a mafia gang” and portraying BBC Persian as an arm of the British state. In addition, journalistic sources within Iran have been targeted.

The authorities also deny the staff the right to travel from Britain into Iran to attend family funerals or to visit ailing relatives and friends. “We are living through a daily nightmare,” says Rana Rahimpour, BBC Persian’s senior presenter. “When a parent dies we cannot go out there to mourn. They arrested my loved ones to force me to leave my job. A judge told my parents you have to stop her [from broadcasting for the BBC].”

Rahimpour’s father was interrogated in 2013 by police trying to discover where she and her husband live in the UK. Then a year-long travel ban was imposed on her parents, which prevented them from visiting their grandchild. It says something for Rahimpour’s bravery that she refuses to back down.

She is aware of despicable threats to some of her colleagues. One was told that the authorities knew where she lived in the UK and that it was possible her son would be killed in a road accident. Unsurprisingly, some people have left the service in the face of such pressure.

“Most, however, have persevered. They know their efforts are appreciated because so many people watch BBC Persian TV. Despite an official ban, some 13 million Iranians, about one in five of the population, watch the output, which includes arts, drama, entertainment and sport as well as news.

“It’s the existence of the channel, its popularity inside Persian living rooms, that draws official fire,” says Tarik Kafala, controller of BBC World Service Languages. The TV service was launched in 2009, which happened to coincide with the beginning of the regime’s crackdown on journalism.

A lawyer acting for the BBC, Caoilfhionn Gallagher QC, concedes that the harassing of journalists and accusing them of espionage or terrorism is a tactic employed by many despotic countries.

But she argues that the BBC Persian case is different, mainly because of “the unprecedented collective punishment of journalists”.

Then there is the collective punishment of people connected to them, whether family, friends or, in the case of journalists, their sources. Thirdly, there is the willingness to take action across national borders.

Gallagher says: “Iran is sending a clear message to journalists that they should stop their work. They should be gagged. They should leave their jobs. Every day when they report to camera or on the website, they know they have this hanging over their heads.”

Fears of what Tehran might do appears well founded. Two months ago, Iran was accused by the Dutch government of directing two political assassinations in the Netherlands. The victims were Dutch nationals of Iranian origin. For Gallagher, these allegations suggest that there is “a very grave risk here to individual journalists”.

A year ago, the BBC appealed to the United Nations over the BBC Persian harassment. It led to a statement two months later by UN secretary-general António Guterres in which he acknowledged that Iran had been guilty of persecuting staff.

Last week, the European parliament voted overwhelmingly in favour of a resolution criticising Iran’s treatment of journalists, and all human rights defenders. It criticised the targeting of BBC Persian staff and demanded Iran “stop the surveillance, arrest, harassment and prosecution of journalists, online activists and their families.”

It is to be hoped that this development helps to push the subject higher up the mainstream media’s agenda. More, much more, should be done ensure that Iran’s assault on press freedom gains greater public attention. To ignore it is to condone it. And allowing it to fester may well encourage other tyrannies to follow suit.

Changing Times

The editor of the Times, John Witherow, has made a rare error of judgment by replacing the paper’s parliamentary sketch writer, Patrick Kidd, with Quentin Letts.

He’s the new Kidd at the Times … but Quentin Letts is the wrong choice. Photograph: David Hartley/Rex/Shutterstock

I understand that I am far from alone in viewing his decision to give the post to Letts, the former Daily Mail man, as a mistake.

According to my inside sources at the Times’s London Bridge office, a host of readers have protested at the loss of Kidd’s carefully crafted daily pieces while decrying those written by Letts.

Emails are said to be running overwhelmingly in favour of Kidd. To quote a Times reader of my acquaintance, who voiced the majority view, the rapier has been displaced by the bludgeon.