Ex-Tory Defence Secretary BLOCKED release of British mother held in Iran, Boris Johnson reveals

While the Treasury and the Foreign Office signed off on the deal, then Defence Secretary and South Staffordshire MP Sir Gavin blocked the deal on the basis that the money might be used to fund the Iranian-backed terror group Hezbollah.

Zaghari-Ratcliffe was finally released in March 2022 when Johnson, as Prime Minister, used his executive authority to revive the deal.

In April 2016, the Iranian-British dual citizen was detained in Iran as she was about to fly back to London after visiting her parents in Tehran as she was falsely accused of spying by authorities.

Boris Johnson appeared before the Foreign Affairs select committee in Parliament as Foreign Secretary in November 2017 and wrongly said Zaghari-Ratcliffe had been in Iran to train journalists.

Johnson was accused of worsening her situation because training independent journalists in Iran is regarded as sedition.

In his new memoir, Unleashed, Johnson claims that this did not result in any further charges being brought against Zaghari-Ratcliffe, nor was her prison sentence lengthened, but he went to Tehran the following month determined to get her home.

He added that Zaghari-Ratcliffe was "trapped by one of those petty power plays that are part of British politics."

In 1979, the Shah of Iran had placed a £400m order for British tanks and armoured cars shortly before he was deposed by the Ayatollah Khomeini. This meant the order was never fulfilled and the money had sat in an escrow account ever since, and the Iranians wanted it back.

Johnson suggested he could arrange for the money to be repaid, though “there could be no linkage” officially with Zaghari-Ratcliffe’s case.

Johnson wrote: "I went to see President Rouhani in his mirror-walled palace and we sat on little chairs facing each other, as if for a TV interview. He was a beaming, soft-spoken man who seemed to have fond memories of his time at university in Glasgow."

After suggesting the £400m could be used, Johnson writes: "Yes, [Rouhani] said, nodding and smiling, there could be no linkage, but perhaps the consular cases could be resolved. I left the meeting elated. I was sure that Rouhani was sincere, and that we had an agreement.”

However, upon returning to London and discussing the deal with then Prime Minister Theresa May, he was met with objection from the Ministry of Defence with Sir Gavin saying: "I won’t send money to Hezbollah so they can buy weapons to kill our boys."

Johnson writes: "It was no use. I have always been friendly with Gavin, who is a keen student of politics and power, and I could see what was really going on. While Nazanin languished in Iranian captivity, with many blaming me, there were quite a few people who were savouring my moral torment – not least, I suspect, in Number 10."

However, when Johnson became Prime Minister in 2019, he said he was met with further issues as, as he writes, "even then, at the last minute, the White House tried to stop us handing over the cash" and banks would not touch the money for fear of falling foul of international sanctions against Tehran and being prosecuted by the US courts.

Johnson remains secretive about how the money ended up being transferred, only saying someone at the Foreign Office came up with a solution and that "it involved the Post Office savings bank."