A nuclear submarine commander 'argued with his superiors' in front of his crew as he organised a welcome home BBQ and disco to welcome sailors home before they went into coronavirus quarantine.

Commander John Lewis held an impromptu party for the crew from the 'hunter-killer' sub HMS Trenchant alongside their boat at Devonport naval base after being at sea for two months.

He is now being investigated by the Royal Navy and faces being stripped of his command.

Lewis, who is in his 40s, has been in charge of the nuclear powered sub for less than a year.

It had just returned from manoeuvres with the mission starting before the UK was put on lockdown to stop the spread of Covid-19.

Despite effectively self-isolating underwater the 150 crew were told they had to do the same at home for a further two weeks.

Commander Lewis arranged the BBQ and disco as a morale booster before shore leave.

A Navy insider said he had been told by superior offices not to hold the BBQ -but ignored their advice and went ahead with the dockside party.

Lewis is understood to have had a 'terse exchange' with his superiors on the phone in front of his junior crew.

'The commanding officer decided that it would help cheer his men up after a long time at sea.

'It was his way of letting them blow of steam after weeks at sea where they had been self isolating anyway. They were told on their return they had to self isolate for a further two weeks.

'Unfortunately, some people higher in command saw this as a lapse of judgement given that most of the UK has been in lockdown and not allowed to have BBQs. It wasn't seen as the right choice to throw a BBQ.

'Senior officers take a dim view of a commander countering an order in front of junior members of the crew.'

Senior officers were said to be particuarly appalled that he allowed crew to film the event and post it to social media.

Footage of the mobile disco on HMS Trenchant (left) was posted to social media. Many of the crew can seen looking on bewildered with their hands in their pockets (right) as the disco blares out music.

Many of the crew can seen looking on bewildered with their hands in their pockets as the disco blares out music.

Cooks in white overalls can be seen standing over a BBQ with the submarine in the background.

The sub had been on patrol for several weeks and returned to its base in the Naval dockyard at Devonport in the first week of April.

A Royal Navy insider said the dockside party is one of several incidents under investigation connected to Lewis.

Lewis had previously been executive officer on another nuclear submarine that was at the centre of a drugs scandal in 2017 when nine crew members tested positive for cocaine.

The sub's captain was also removed while an investigation into an alleged affair with a female crew member was carried out.

HMS Trenchant is one of three nuclear powered subs in the Navy's arsenal.

The Trafalgar class submarine is equipped with Tomahawk cruise missile, which can destroy a target from up to 1,000 miles away.

HMS Trenchant is one of three nuclear powered subs in the Navy's arsenal

Powered by a nuclear generator it can stay underwater for months with only food replenishment for the crew making it surface.

In 2018 the sub broke through the ice of the North Pole after a joint exercise with the US Navy.

One of the crew posed for a photo holding a cricket bat on the ice cap.

A Royal Navy spokesman said: 'An investigation is underway. It would be inappropriate to comment further.'