British-Iranian nationals Nazanin Zaghari-Ratcliffe and Anoosheh Ashoori are back in the UK after being freed from years of Iranian detention.
The pair touched down at RAF Brize Norton in Oxfordshire just after 01:00 GMT on Thursday.
Their release came after months of negotiations between the British and Iranian governments.
After leaving the plane in good spirits, they met their families in the airport for the long-awaited reunions.
A picture taken inside the airport and posted to Twitter by Mr Ashoori's daughter, Elika Ashoori, showed both returnees standing in a group with their relatives.
The caption read: "Happiness in one pic."
Ms Zaghari-Ratcliffe's seven-year-old daughter Gabriella could be seen with her arms round her mother's neck.
Speaking from the airport, UK Foreign Secretary Liz Truss said the pair's release had been uncertain until the "last minute", adding that recent days had been "very emotional" for both families.
"I'm pleased to say that both Nazanin and Anoosheh are in good spirits," she said.
"I thanked the families for how stoical they've been during this really, really difficult period. It's so fantastic to welcome them back safe and well here in Britain."
Ms Zaghari-Ratcliffe, 43, and Mr Ashoori, 67, left Iranian capital Tehran for the UK via Oman, shortly after being freed on Wednesday.
It marked the end of an ordeal that, for Ms Zaghari-Ratcliffe, a project manager for the Thomson Reuters foundation, began in 2016 when she was accused of plotting to overthrow the Iranian government.
In April last year, she was sentenced to a further year in prison and a one-year travel ban on charges of propaganda against the government.
Mr Ashoori, a retired civil engineer, was detained in 2017 on spying charges and sentenced to 10 years in prison.
Both Ms Zaghari-Ratcliffe and Mr Ashoori have always denied the claims against them.
Their freedom comes after the UK government settled a historical debt to Iran of almost £400m - although both countries have said the payment should not be linked to the pair's release.
The debt dated to the 1970s, when Iran ordered 1,500 British Chieftain tanks and 250 armoured recovery vehicles from a subsidiary of the UK Ministry of Defence.
After the Iranian revolution in 1979, the UK cancelled the order, having delivered only 185 tanks. Iran then demanded their money back for the undelivered vehicles.
On Wednesday, Ms Truss called the debt "legitimate" - and said it and the detainees were "parallel issues in our bilateral relationship [with Iran]".
She said the money would be paid "in full compliance" with sanctions on Iran, and would "be ring-fenced solely for the purchase of humanitarian goods".
A second man, Morad Tahbaz, who has Iranian, UK and US nationality, was released from prison but is not yet allowed to leave Iran. Ministers have vowed to continue to push for his return home.
The 66-year-old businessman and wildlife conservationist was accused of collecting classified information about Iran's strategic areas under the pretext of carrying out environmental and scientific projects, which he denied.
Writing on Twitter, Ms Truss said: "Pleased Morad Tahbaz has been released on furlough and is reunited with his family in Iran, but this is far from sufficient. We will continue to work intensively to secure his departure from Iran."
Speaking before Ms Zaghari-Ratcliffe's return to the UK, Mr Ratcliffe said he was "deeply grateful" for his wife's release and that it would be the "beginning of a new life" for their family.
He said Gabriella had picked out which toys to show her mother when the plane landed, and that one of the first things he would do was make his wife a cup of tea.