Between 2016 and 2017 the UK’s Foreign and Commonwealth Office provided consular assistance to over 23,000 British citizens caught-up in trouble abroad; in any given year some 6,000 of those will find themselves imprisoned. Thousands of these Britons will have travelled overseas to countries with unfamiliar, often conservative laws and marked cultural differences only to find themselves in police custody and often held in dire conditions. In the vast majority of cases, this is a result of either genuine ignorance or a deliberate disrespect for local law, or of universally criminal behaviour that would just as likely have landed them in a cell at home. None of this applies to Nazanin Zaghari-Ratcliffe.

Nazanin’s arrest had as much to do with EU sanction negotiations, Cold War-era politics and the perennial arrogance of Western foreign policy as the now Oxford-educated Sandra Gregory’s infamous imprisonment in Thailand had to do with drug trafficking. In other words, the 41-year old British-Iranian is a political prisoner, plain and simple. This is a truth that even the British government—whether through strategy or lack of impetus—refused to outwardly recognise until 2019, when she was finally granted diplomatic protection. This status—distinct from diplomatic immunity—represents a legal recognition that her imprisonment had little to do with the individual and everything to do with her nationality. It effectively acknowledges her a chess piece in a geopolitical game.

Her story is well-known: a dual Iranian-British citizen, Nazanin Zaghari-Ratcliffe was arrested in Tehran in 2016 whilst boarding a flight home to London, following a visit to her parents with her infant daughter. After a show-trial before a secretive and highly politicised Iranian court she was falsely accused of espionage and condemned to five years in the city’s infamous Evin prison. As ever, there is more to the story: the 41-year old’s detainment is embroiled both in current geopolitical events and in the history of UK-Iran relations.

In recent years, this relationship could have been described somewhat optimistically as fraught. The primary sore point (of many) is predictable: money. In 1971 the United Kingdom entered into a major arms deal with pre-revolutionary Iran, receiving £450 million in payments for military equipment produced by British firms. The vast majority of that equipment never arrived. Politically, the reason is fairly simple: Iran’s regime changed in the hugely consequential revolution of 1979 and Thatcher’s Conservative government treated the Gulf state’s new hard-left leadership with suspicion and—perhaps more pertinently—so too did the Carter administration in the US. In a move that smarted as much of derisive colonial arrogance as it did of dodgy phone-shop dealings, the Iron Lady’s government pulled the plug on the order, sold the remaining equipment to Iran’s regional nemesis, Iraq, and—crucially for Nazanin’s story—kept the money.

Fast forward several armed conflicts in the Gulf, a 2002 arbitration ruling in Iran’s favour and numerous disastrous Iranian Revolutionary Guard-Royal Navy clashes and—as of March 2020—the debt remains unpaid. The UK government paid the balance into a court-supervised, frozen account following the 2002 ruling, but refused to transfer it on to the Iranian government, citing now long-standing financial sanctions imposed on the Republic of Iran by the EU. Just months before Zaghari-Ratcliffe’s arrest in 2016, the Gulf nation established a seemingly effective precedent of ‘hostage diplomacy’ in order to attenuate a similar financial dispute with the US, successfully extracting a $400 million debt from the Obama administration, flown to Tehran in cash the day before the release of 5 similarly arbitrarily held American citizens.

With that in mind, the wood beyond the trees of Zaghari-Ratcliffe’s detainment, and that of four other British-Iranians like her, begins to come into sight. The problem in Iran’s recourse to what is effectively ‘hostage diplomacy,’ however, is that EU sanctions had frozen Iranian assets in Europe and banned the transfer of funds, meaning that, until recently, both Downing Street’s hands and its purse strings were tied. Events have accelerated in recent weeks and along with Zaghari-Ratcliffe’s temporary release on house-arrest, we have seen this week’s hearing of Iran’s debt case in the UK court of appeal, the uncontrolled spread of COVID-19 within Iran, the politically explosive assassination of Qasem Soleimani and, of course, the UK’s exit from the European Union.

At the most basic human level, we can all sympathise with the 41-year old’s horrific experiences: prolonged separation from her family, severe trauma, physical mistreatment and her exposure to the coronavirus, all whilst living under dire conditions in the Iranian prison system. Yet this story is likely to end the way it began, with Nazanin as a person being far less important to the Iranian regime than Nazanin as a valuable piece in a geopolitical jigsaw puzzle. Ultimately, politics imprisoned her, and it will be politics that allows her to return home.

Indeed, if she does return home, the UK government will need to consider what lessons can be learned here. Rightly or wrongly, principle almost always plays second fiddle to pragmatism in geopolitics and it is likely that, following Nazanin’s return home, relations between Tehran and London would improve. This seems unavoidable given the general desire in Whitehall to avoid a return to 2011-15, a period defined by closed embassies and diplomatic radio silence between the two countries. With that said, the Iranian government has demonstrated a nefarious disrespect for the distinction between the personal and the political. Tehran has illustrated time and again that it is willing to prey on individuals in order to hit at foreign governments. International Relations theorists often speak in terms of Idealism and Realism: it is a reality that political dealings with Iran have the capacity to put individual British citizens—especially those with dual citizenship—in serious jeopardy. Wrong though that may be, government must accept this, be realistic and place the safety of individuals at the heart of its policy making.

But again, in real terms, what does that actually mean? In the first instance, policy on Iran must be preventative, it must mitigate the risk to individuals: the UK’s debt must be settled, in some form, as a matter of priority. Any ongoing dispute of this kind clearly poses a real and demonstrable threat to British citizens travelling in Iran. The Secretary of State for Defence, Ben Wallace, has suggested that this might be achieved by providing the equivalent sum in humanitarian aid. If agreed, this solution would contribute to the wellbeing of both Iranians and Britons alike, but Brexit seriously undermines of the UK’s use of EU sanctions to justify excluding cash payments, so whether or not Tehran would look kindly on any quid pro quo aid arrangement seems uncertain.

Failing prevention, however, looking across the channel to Emmanuel Macron’s government may provide solutions: through a combination of leveraging her influence in mediating US-Iran talks and an agreed prisoner swap, France—which has no outstanding debt to Iran—was able to secure the release of Sciences Po’s Professor Fariba Adelkhah within just nine months. Tehran offered London a similar arrangement for Zaghari-Ratcliffe’s last year, but to no avail. Prisoner exchanges such as this, although some may voice moral objections, are the only proven way of successfully mitigating Iranian aggression towards individuals. In principle, prisoner exchanges with Iran would mean operating on Tehran’s diplomatic and moral plain, by employing individuals as devices in bilateral political games. But once a political prisoner has been taken, such principles surely should bow to the pressing reality of the situation.

In real terms, if we are to avoid further cases like Nazanin’s, government must put idealistic principles aside—prisoner exchanges speak to Tehran in a language it understands. Like many of those 6,000 Britons who find themselves imprisoned overseas each year, the UK government must, when dealing with countries like Iran, be more willing put its own values aside and conform in the interests of safety.