A British-Australian academic is still being held in Iran while another British-Australian woman and her Australian boyfriend have been released from detention.
Tehran has pursued a campaign of detaining Iranian and dual nationals academics in recent years, raising fears the Islamic republic is using them as diplomatic leverage.
While there are no exact figures on the number of detainees with British links being held in Iran, these are at least some of those who are understood to be incarcerated as part of Iran's "hostage diplomacy".
Ms King was camping with her Australian fiance Mark Firkin near a military site in Jajrood near Tehran when the pair were arrested by the Revolutionary Guard on August 9 for reportedly flying a drone without a licence.
The couple, who live in Perth, Western Australia, had been travelling across Asia for months, chronicling their journey regularly on YouTube and Instagram.
They were released and all charges droppedafter almost two months in prison in Tehran, Marise Payne, Australia's foreign minister, announced.
At the same time as Ms Payne announced the release of Ms King, the minister also said British-Australian Kylie Moore-Gilbert was still in Tehran's notorious Evin prison.
Dr Moore-Gilbert, who was working as a lecturer and researcher for Melbourne University's Asia Institute and has published work on authoritarian governance and activism in the Middle East, was jailed in October 2018.
However, her detention had not been reported in case it harmed the prospects of her release.
She has been sentenced to 10 years in jail. It is not known what Dr Moore-Gilbert was charged with, but 10-year terms are routinely given in Iran for spying.
The most high-profile detainee, Mrs Zaghari-Ratcliffe has been held on spying charges since 2016.
Mrs Zaghari-Ratcliffe, a British-Iranian charity worker, is incarcerated in the Evin jail and is now only able to see her five-year-old daughter, Gabriella, once a month.
The Free Nazanin campaign also said she is barred from making international calls, leaving her unable to speak to her husband Richard, who has been campaigning for her release from the UK.
Tulip Siddiq, who is Mrs Zaghari-Ratcliffe’s Labour MP, told The Times that the latest detentions of the Australian-British women, was "s a clear escalation of Iran’s hostage diplomacy".
Mr Ratcliffe criticised Boris Johnson for not meeting with the family since he entered Downing Street last month. He said there had also been no invitation to meet Dominic Raab, the new foreign secretary.
During his tenure as foreign secretary, Mr Johnson incorrectly said Mrs Zaghari-Ratcliffe was teaching journalism in Iran.
His comments were seized upon by Iranian prosecutors who brought them up in court as evidence against the charity worker. Mr Johnson later apologised for the remarks.
Mr Tahbaz, an Iranian-American businessman who is believed to hold a UK passport, was arrested in 2018 during a clampdown on environmentalists and academics.
The authorities accused Mr Tahbaz and seven other conservationists of collecting classified information about Iran's strategic areas under the pretext of carrying out environmental and scientific projects.
The conservationists, members of the Persian Wildlife Heritage Foundation, had been using cameras to track endangered species, including the Asiatic cheetah and Persian leopard, according to Amnesty International.
Mr Foroughi has been detained in Iran for alleged espionage charges since 2011. Two years after his arrest, he was convicted of espionage and possessing alcohol.
The 80-year-old grandfather strenuously maintains his innocence.
3rdSep: Happy 80th birthday Dad!! Ruz-e Tavalod-e mobarak! pic.twitter.com/UB76ipws1z
— Kamran Foroughi (@FreeKForoughi) September 2, 2019
Mr Foroughi, who came to Britain in the 1970s, also holds an Iranian passport. Before his arrest, he was working in Tehran as a consultant to Petronas, the Malaysian oil company.
He has been eligible for release for several years under Iran's own laws. However, it is believed he is still in jail, the BBC reports.
Ms Amiri, an Iranian woman who worked at the British council, is also being held in Evin prison.
The 33-year-old was arrested on spying charges in 2018 and was sentenced to ten years in prison in May for “cultural infiltration by the British intelligence services in Iranian internal affairs”. She strongly denies the allegations.
In August she lost her final appeal against espionage charges before Iran’s supreme court.
Ms Amiri had appealed against the sentence in a letter to the head of Iran’s judiciary but the supreme court ruled to uphold her conviction and her prison term.
She said in her letter that she was arrested because she refused to cooperate with Iranian intelligence officials who wanted her to spy for them in Britain.
“I directly rejected their offer for cooperation and told them that I can only work in my own field and nothing else,” she wrote.
Iran often tries to pressure its expatriate citizens to cooperate with intelligence work.
A British-Iranian anthropologist, Mr Ahmady was arrested in August and also taken to Evin prison. Charges against him have not yet been made public.
Mr Ahmady, an Iranian Kurd who was born in the western city of Mahabad, was granted British citizenship in 1994 but had been living in Iran for the last 14 years.
His wife, Shafagh Rahmani, said at the time he had not been officially charged, but prosecutors at Evin prison said that he faces a series of charges related to “his activities”.
According to his Linkedin profile, Mr Ahmady, who had studied at the London School of Economics, is "a scholar working in the field of social anthropology conducting research on topics related to local cultures, women and children, and the rights of minorities in the Middle East, with some work experience in Africa and the Far East.”
In August, Iran’s judiciary said it had sentenced London businessman Anousheh Ashouri, 65, to 12 years for allegedly passing information to Israel’s Mossad intelligence agency.
Mr Ashouri has been detained since August 2017 but was sentenced in August by a court in Tehran, which accused him of “being connected to Mossad and receiving money from them as an informer.” The judiciary did not make public the evidence against him.
His daughter Eilka, an actress living in London, said her father, a businessman who has lived on-and-off in the UK since the age of 17, was in Iran visiting his mother when he was detained.
“My father has nothing to do with politics and told us not to get involved in politics," she said, adding that her father had run a building supplies company before he retired.