Why did Boris Johnson give the incorrect answer about what Nazanin Zaghari-Ratcliffe was doing in Iran? To quote Michael Gove, “I don’t know”. Whatever the reason – a misreading, winging it, or anything else – it’s obvious that the Foreign Secretary made a serious mistake which could well have severe consequences for a British citizen who is already in a dire situation.

The ultimate responsibility for Zaghari-Ratcliffe’s suffering lies with the murderous theocracy which has imprisoned and mistreated her, but Johnson has given the Iranians an excuse to extend that nightmare. Excuses are the essential fuel for any given tyrant’s propaganda effort. Anything to muddy the waters, to cast suspicion, to deploy smokescreens, or to imply a false moral equivalence between a tyrannical regime and its democratic critics. The Foreign Secretary’s error helped our enemies and harmed an innocent victim of tyranny.

It’s perfectly reasonable and merited to criticise Johnson for that failing. That doesn’t mean we should indulge every demand and attack on him, however. There’s a deal of political game-playing underway, despite the seriousness of the situation.

Jeremy Corbyn, displaying further signs of his evolution into a politician, is making hay on the story with opportunistic gusto. Frankly, a man who was paid thousands of pounds by the propaganda wing of the regime torturing Zaghari-Ratcliffe is in no position to lecture others about “undermining our country” or “putting our citizens at risk”. But nonetheless, he persists.

More than a few others who had previously taken no notice whatsoever of Zaghari-Ratcliffe’s plight are now in full outraged mob mode. That is not due to a belated flowering of interest in human rights in Iran. Rather, some see an opportunity to score points on the issue they actually care about, and for which they cannot forgive Johnson: Brexit. That’s life for a prominent politician – there’s always somebody out to get you – but it doesn’t mean their words should be obeyed automatically.

We must be clear-sighted and rational about what comes next. Consider how Iran would most like this situation to develop, then try to do the opposite.

Richard Ratcliffe is of the view that Tehran is using his wife as a “bargaining chip”. He’s right, of course – the theocracy has a long history of taking hostages and prisoners on trumped-up grounds, and effectively bartering them for prestige or political advantage.

So far, Iran’s exploitation of Zaghari-Ratcliffe has broadly served their purposes. Johnson’s error has undeniably handed them a bonus, ramping up the political value of their captive by creating a greater demand in the UK that the matter be resolved.

There’s now a danger for the UK – the risk that the scale of the political response at home could effectively give Iran the final say over the British Foreign Secretary’s future. That’s what Michael Gove was driving at yesterday when he cautioned against “shift[ing] the blame away from Iran and onto a democratically elected politician”. If that happens, not only could it make things even worse for Zaghari-Ratcliffe by incentivising Iran to further mistreat her, but it would effectively grant far greater power to a deeply unpleasant, hostile state.