British couple jailed in Iran: 'We're likely to be here for a long time'

Despite her doctorate in positive psychology, which she says has given her tools to help her handle the ongoing ordeal, there are days of dark despair.

She breaks down in tears as she tells me: "There are people who have been here for years, and it's just so unfair."

Craig, who can hear what she is saying on speaker phone from another of Joe's phones, quickly jumps in to comfort her.

"We can do this," he tells her. "We will do this. We'll get through it together and, sometime, I hope soon, we will be on the other side of these walls. So stay strong, my love."

The couple say they were on a motorbike journey from Europe to Australia when they crossed from Armenia into Iran, intending to stay only for a few days. Lindsay was asking people along the route what constitutes a "good life" and was due to present her findings at a conference in Brisbane.

It was this line of questioning that appears to have got the pair into trouble with the Iranian authorities.

The couple had been aware of Foreign Office advice that British nationals should not travel to Iran.

"Craig and I had assessed the risk and did not think that innocent tourists would end up in prison for this long with no evidence," Lindsay says. "I take responsibility for the choice I made to come here, and I have to live with the consequences."

She says it would be hard for anyone who has not been through jail in Iran to truly understand those consequences.

Lindsay spent an initial 57 days of detention in solitary confinement in the city of Kerman. Craig was interrogated while blindfolded during his time in solitary confinement, something he describes as "horrific".

They were moved to the Iranian capital Tehran last July, and told they were being freed, only to find themselves in the capital's notorious Evin prison.

The prison is where Nazanin Zaghari-Ratcliffe, the British-Iranian mother, was also held during her six years in jail in Iran.

Lindsay and Craig say that conditions in Evin prison are better than solitary confinement, but are still tough.

"It's not very hygienic. There's no health care, no dental care," Craig says. "And there are lots of fights between inmates. You have to try and stay clear because there are homemade weapons and things."

Both say they are well aware that many Iranians are suffering more than they are.

One of Linsday's cellmates was sentenced to death for her role in nationwide protests in January, which the regime crushed with lethal force, killing thousands.

"It's frightening," she says. "When I look at my position, I think 'well, thank God I didn't grow up here'. There will be an end for us at some point. But for some of these people, there won't be an end."

Since he was moved to Evin prison last summer, Craig says four of his cellmates have been taken away for execution.

"I know they've been executed because they publicise it on TV the next day," he tells me.

"We're in a horrible position right now, but we have met some fabulous people along the way," he says. "We have seen both sides of this country firsthand."