"Nazanin Zaghari-Ratcliffe and the other British dual nationals held in arbitrary detention are being held by Iran. It is on them."

It is not lost on anyone – Nazanin's family, Tulip Siddiq, this newspaper – that Iran is the real villain in Nazanin's case.

As Richard Ratcliffe said this week, her detention is, in truth, a "crime against humanity".

But Iran's guilt does not absolve the British government of its failure to protect its citizens.

The endless setbacks in the quest to see Nazanin freed have long felt suffused with an inevitability - of course it is the UK that is unable to get its people out of the clutches of the Iranian regime, of course the UK government is the one making out that criticism of its actions are political point-scoring.

Nazanin-Zaghari-Ratcliffe-given-further-one-year-term-in-Ira

We are always told that the British government is doing "everything it can" - but how can this be true when, asked directly, ministers refuse to call Nazanin a hostage or call her treatment torture.

James Cleverly this week said Nazanin's had been through a "cruel and inhumane ordeal". That, to me, sounds like torture by another name.

So why can't he say that? And if they won't speak plainly, how can we have confidence that, as Boris Johnson has always promised, "no stone is left unturned".

Tougher words from the Prime Minister may not help, tougher actions may not help, but it does not appear that British leaders have tried either.

Members of Boris Johnson's own party - including noted lefty-liberal crusader Jeremy Hunt - called on the government to start explaining the consequences of holding Nazanin, Anoosheh Ashoori and others like them to Iran.

This should mean threats of sanctions, of scuppering Iranian hopes to revive the nuclear deal, because simply: what is the point of international diplomacy if it doesn't stop a rogue state locking up whoever it wants?

The Iranian regime clearly does not care what the UK says, when it comes to Nazanin. It may not care what the UK does - but until our government actually does everything it can, we will not know either way.

Holding people hostage should have consequences.