Royal Navy chief Admiral Sir Ben Key was suspended from his duties amid claims he had an affair with a subordinate officer.

The suspension has rocked the Navy as this is the first time in its illustrious 500 year history that its chief has faced a misconduct probe.

Admiral Key, 59, is alleged to have broken the Navy's strict code of conduct by engaging in a sexual relationship with a subordinate.

A source told The Sun: “He is under investigation over an alleged inappropriate relationship with a female officer under his command."

The father-of-three was due to be replaced by Royal Marine General Gwyn Jenkins in the summer, but has been prevented from resigning early in order to allow the investigation to run its due course.

Vice Chief of Defence Staff, General Dame Sharon Nesmith, will lead the inquiry despite holding the same rank as the accused.

The military normally requires investigations to be carried out by more senior officers, but in this case the only person of higher rank to Admiral Kelly is the Chief of Defence Staff Admiral Sir Tony Radakin.

“In theory Ben could still be court martialled for bringing the Navy into disrepute, but that seems very unlikely at this point," the source added.

“He has served his commendably for over 40 years. The investigation is still ongoing. There is no whiff of anything criminal.”

The last time an admiral faced a court martial was in 1757 when Admiral John Byng was convicted and executed by firing squad. He was charged at the time with “failing to do his utmost” to prevent French forces from capturing Minorca.

It is understood that the woman in question is a senior officer but junior to Admiral Key.

Appointed First Sea Lord in 2021, Admiral Key has repeatedly promised to clamp down on unacceptable sexual behaviour.

In 2022, he said he would expel anyone who refused "to serve in accordance with the values and standards of life in the United Kingdom’s armed forces."

He reinforced that message just last year, when he declared “zero tolerance for unacceptable behaviours”.

He joined the Navy as a cadet in 1984 and commanded two frigates, a minehunter and the aircraft carrer HMS Illustrious.

A veteran of the Iraq war, he was awarded a US Bronze Star and oversaw the retreat from Afghanistan, codenamed Operation Pitting, immediately before taking over the Navy.