Erik Hanell took the call 10 minutes after leaving the Swedish company's office in Gothenburg on Friday, 19 July.

It was a member of technical manager Northern Marine's emergency team in Glasgow, saying Iranian authorities were approaching the 50,000-dwt MR tanker Stena Impero (built 2018) in the Strait of Hormuz.

Stena Impero timeline

11 July: Iran tries to seize BP tanker in retaliation for Grace 1 seizure in Gibraltar

19 July: Stena Impero boarded by Iranian forces

23 July: Stena still awaiting permission to visit seized crew

25 July: UK commits to escorting its ships through Middle East Gulf

25 July: Stena in direct talks with Iranian authorities

15 August: Gibraltar court allows release of Grace 1

21 August: Stena Bulk chief executive Erik Hanell meets Iranian foreign minister Javad Zarif

4 September: Iran releases seven Stena Impero crew

23 September: Iran says tanker now ready to be released

27 September: Stena Impero leaves Iran for Dubai

So began a baffling and frustrating 71-day saga as the shipowner fought through layers of murky bureaucracy to free the vessel and its 23 crew.

The chief executive of Stena Bulk told TradeWinds that the company was operating five or six vessels in the region at the time, of which more than one was UK-flagged.

Iran had just threatened to detain a UK-flagged or owned vessel in retaliation for the detention of its 301,000-dwt VLCC Grace 1 (built 1997) in a row with the European Union over Syrian sanctions.

"At any given time and at that time as well we are always doing risk assessments, with the British flag and UK authorities," Hanell said.

"The threat is one thing, but the situation in the area in general is what we are considering both at the time and today as well."

Emergency teams scrambled

Regarding the first phone call, he said: "This was in the afternoon. I had just left the office on my way for some time off actually.

"I got a call from our emergency team in Glasgow about 10 to 15 minutes after leaving the office."

He was told that Iranian, British and Omani navies were calling the ship, and the Iranian navy was approaching the vessel as well.

"They made some calls for the ship to head towards Iranian waters because they wanted to talk to the ship," Hanell told TradeWinds.

"I could hear the conversation from the ship at the time from the captain, so we got updated minute by minute.

"A lot of things were going on, but about 5pm that evening I got the call from Glasgow again saying the ship had been boarded by the Iranian navy."

He added: "It was surrealistic to a quite high degree, but at the time as well the question marks are quite big and you wonder, why, and what is going on?

"At that moment in time we didn't have any information and the questions are coming up directly: have we done something wrong?

"And the immediate answer from Glasgow was, as far as we know, nothing."

Then, he said, came the wait from the Iranian authorities as to why the vessel had been seized.

Asked if he had any sense then of being in the middle of the biggest story in the world at that time, he told TradeWinds: "Absolutely not. My immediate reaction was, well, this has to be a misunderstanding somehow and it will be sorted out within a couple of hours."

The Stena Impero under detention in Iran Photo: Tasnim News Agency

Controlled chaos

He said: "It was controlled chaos, I would say. Northern Marine, they were basically up and running with the emergency team already.

"When I got the phone call I called my emergency team and within 15 minutes we were all up and running. Remember, this was the middle of the summer and in Sweden at least, vacation time, so the emergency team was spread around the world."

Hanell added: "But nevertheless we were definitely online and taking the first couple of steps within 30 minutes, setting everything up. The focus was to get information from the ship and the Iranian authorities.

"It took another 20 minutes after that before the media started to call.

"We said we don't have any comment right now, we have to investigate what's going on."

The Stena Bulk website was switched over to provide updates and media company MTI handled news releases.

The next morning, Hanell decided he would respond to press enquiries, doing 50 or 60 interviews per day for the first four or five days.

Relentless media pressure

"The media pressure was enormous I have to say," he said.

"Phone calls continuously for 24 hours. I got a few hours in the night time, but in between there was a lot of decision making, trying to find out what was going on. Some sleepless nights for sure the first week."

He said the most challenging thing in the beginning was that the company could not get in touch with the Iranian authorities at all.

"I think it took two or three days and then we at least got some response from the ship and some feedback from the Iranian authorities as well, that they had received our letters asking that the ship should be released."

Stena Bulk did not have any of its people (besides the crew) onboard at all during the 71 days of the detention, but it had local representatives through a ship agency and the protection and indemnity mutual Swedish Club, as well as staff from embassies representing the crew.

"From that respect we got good reporting, but not direct contact," he said. "The crew were allowed to call their relatives and families on a daily basis. And we got some information from that as well."

Crew treated okay

Hanell said: "Physically the crew were treated okay, but the unknown — what's going to happen and how long is it going to take — that would put anyone into quite a high pressure psychologically."

Hanell said the crew tried to continue to maintain the tanker as far as they could, but it is the newest vessel in the fleet and there was only so much they could do.

"I'm sure there were quite a few hours when they were sitting and waiting as well, but they tried to get into their normal routines as quickly as possible," he said.

"I'm sure they all had their moments when it was very tough and they were thinking, when will we be released, what's going on, and what kind of developments are we seeing in the near future?

"They did what they could and supported each other onboard."

As for his own efforts to move the situation forward, he said: "Especially the first couple of weeks it was very frustrating because we did not have any direct contact with Iran.

Meeting sparks progress

One major step came when the Swedish government managed to arrange a meeting between Hanell and the Iranian foreign minister Javad Zarif in Stockholm on 21 August.

"From that time, we saw some progress," Hanell recalled. "It was going slow but at least it was inch by inch in the right direction.

"I had expected it to be released more quickly than 71 days, but we had a good dialogue from that day and got feedback about what was going on.

"I was more and more hopeful."

The release of the Grace 1 in Gibraltar days before this meeting was another major turning point, but Hanell would not be drawn into political questions, refusing to speculate on why his ship was targeted.

"Grace 1 was one speculation; other speculations were that we did something wrong," he said. "There has been talk of fishing boats, that we turned off our AIS. We have not found anything to show we have done anything wrong.

"We are avoiding getting into that discussion. We want to stick to trading our ships."

In early September, Iran allowed seven crew to go home.

Hanell said the core crew of the ship comprised only 15 people, so some extra officers and ratings onboard were released.

By this point, Iran was indicating that a release was imminent, ramping up the intensity for Hanell and his team.

"It was a lot of work for sure," he said. "The last couple of weeks were very intense too.

"That last week, for some reason, felt extremely slow. I don't think it was much slower than before but we knew, well we hoped, that the release was very close."

The vessel was finally allowed to sail to Dubai on 27 September.

'Nice feeling'

"When we finally got the news, that feeling was of course very nice, also for the crew and their families and relatives and friends who were waiting in Dubai with us, and for the team working with this for the last 71 days," Hanell said.

He said the crew were "very happy to be there".

A debriefing took place after a couple of days and the seafarers indicated they wanted to continue in their jobs.

"They all want to be home for a while but they are all definitely ready to go out to sail again," Hanell said.

He added that he is hoping the Stena Impero can be ready to trade again this week.

"We are making sure everything is working okay, going through all the equipment onboard," he said. "We had to take care of that for six or seven days and get the new crew on board."

Sticking with the UK

As for the future of Stena's vessels in the region, Hanell said nothing has changed in terms of risk assessment, but everyone in the area has "stepped up to another level".

The company has not considered changing from the UK flag as a result of the incident.

"We have a good dialogue with the flag and the UK authorities, and the escorts with the UK navy has made a difference," he said.

"We still have five or six ships going in and out of the area at any time. To not go there would be rather challenging for us."