Iran was able to capture a British oil tanker because it only gave the Royal Navy 1 hour's notice to escort it, rather than 24, former UK Defence Secretary says

Joel Rouse/UK MOD

HMS Montrose, which has accompanied dozens of British ships through the Strait of Hormuz amid tensions with Iran.

• The former UK Defence Secretary has offered more insight into how Iran's Revolutionary Guard corps were able to seize a British oil tanker in the Strait of Hormuz last month.
• In a diary extract for The Spectator magazine, Penny Mordaunt said the Stena Impero gave the Royal Navy just one hour's notice before it entered the strait. Other ships had given around 24 hours.
• As a result the navy had to scramble to escort the Stena Impero, and was too late to stop it from getting seized by Iran's Revolutionary Guard, she said
• The Stena Impero and its 23 crew members remain in the south of Iran. The UK this week ruled out swapping the ship for an Iranian tanker seized in the Mediterranean.
• Visit Business Insider's homepage for more stories.

Iran managed to seize a British oil tanker partly because of the tanker's decision to only give the British Royal Navy one hour's notice to escort it, according to Britain's recently-departed Defence Secretary.

Penny Mordaunt, who left her post last week, said that the Stena Impero made it impossible for Britain's HMS Montrose to effectively escort it by giving far less notice than other ships.

Writing in The Spectator magazine, Mordaunt described being briefed on the incident by a senior Royal Navy officer. She said the Montrose sailed as fast as possible to catch up with the Impero, but could not get there before Iran's Islamic Revolutionary Guard Corps (IRGC).

The guard seized the Stena Impero in the Strait of Hormuz on July 19, in apparent retaliation for the UK's seizure of an Iranian tanker, the Grace 1, off the British territory of Gibraltar two weeks before.

Reuters

The Stena Impero, a British-flagged vessel currently seized by Iran's Revolutionary Guard, pictured on July 19, 2019.

Writing in the diary, Mordaunt said that the Montrose had been escorting dozens of British-flagged tankers around the time the Montrose was captured, but in each case had been given 24 hours notice, rather than one.

Upon being informed of the Stena Impero's journey, HMS Montrose sped up to escort the oil tanker, but by then it was too late, Mordaunt said.

"Despite increasing to flank speed, she [HMS Montrose] was 20 minutes too late and steamed into the Iranian Revolutionary Guard," Mordaunt wrote. Flank speed is as fast as a ship can go.

"The anger and disappointment is evident in the Commodore's voice as he professionally delivers his report," Mordaunt said, referring to Commodore Dean Bassett, the UK maritime commander in the Gulf region who told her of the Iranian seizure.

Morteza Akhoondi/Tasnim News Agency via AP

An Iranian Revolutionary Guard speedboat moving around the Stena Impero in Bandar Abbas port, Iran, on July 21, 2019.

A spokesman for the British Ministry of Defence confirmed to Business Insider that all ships passing the strait have to notify the Royal Navy to ensure an escort.

He declined to specify how much notice ships typically give befor transiting the strait.

Business Insider has contacted Stena Bulk, the company operating the Stena Impero, for comment.

Mordaunt was fired from her role as Defence Secretary last week when Boris Johnson became Prime Minister. Ben Wallace, a former security minister, has replaced her.

Jack Taylor/Getty Images

Penny Mordaunt.

As of Tuesday, the Stena Impero remains anchored at Bandar Abbas port in southern Iran, with its 23 crew members inside, the vessel's operator Stena Bulk said.

The crew are unharmed, Iran and Stena Bulk have both said. Last week Iranian state TV aired footage of what it said was the Stena Impero crew cooking and holding meetings on the vessel after the capture, in an apparent effort to demonstrate their wellbeing.

Tehran has also released dramatic footage of its forces seizing the tanker and interrogating the crew.

The incident contrasts with a previous one where HMS Montrose did fend off the IRGC.

On July 11, the Montrose repelled three IRGC gunboats which had been harassing a BP oil tanker, reportedly by positioning itself in front of the Iranians and pointing its deck guns at them.

Read more: Iranian gunboats backed away in a showdown with a Royal Navy frigate after staring down the barrel of the 'perfect weapon'

Mick Storey/Royal Navy/Handout via Reuters

HMS Montrose off the coast of Oman on March 22, 2005.

Earlier this week Dominic Raab, the new UK Foreign Secretary, ruled out the idea of giving Iran its tanker back in exchange for the Stena Impero to end hostilities.

Raab said there would be "no quid pro quo." He argued that the Royal Marines intercepted the Grace 1 lawfully, but that the Stena Impero was seized illegally.

Read more: Britain rejects swapping seized oil tankers with Iran, 4 days after Prime Minister Boris Johnson's father said it would be 'easy peasy'

The Grace 1 is accused of carrying Iranian oil to Syria in breach of EU sanctions. Iran claims it seized the Stena Impero after it collided with an Iranian fishing boat, a charge both the UK and Stena Bulk has denied.

A second Royal Navy ship, the destroyer HMS Duncan, arrived in the Gulf last Sunday to assist HMS Montrose, the UK Ministry of Defence said.

HMS Kent will replace the Duncan in September.