The Queen is facing mounting calls to strip the Duke of York of his honorary military roles after more than 150 veterans joined forces to express their outrage.

In an open letter to the Queen, former members of Royal Navy, RAF and Army described their “upset and anger” at Andrew retaining the titles, saying his position was “untenable”.

They made a heartfelt plea, saying: “Please  do not leave it any longer.”

Accusing the duke of bringing the services he is associated with into disrepute, they added that “were this any other senior military officer it is inconceivable that he would still be in post”.

The duke is facing a high profile civil sexual assault trial after a judge ruled on Wednesday the case could go ahead. Andrew denies the allegations.

The Queen is head of the Armed Forces, and honorary military appointments are in her gift.

Buckingham Palace declined to comment. The Palace said previously that the duke’s military appointments are in abeyance after he stepped down from public duties in 2019.

But he still retains the roles, leaving eight British regiments, including the Grenadier Guards, in limbo more than two years on.

In the letter released by the anti-monarchy group Republic, the 152 former servicemen and women wrote: “We understand that he is your son, but we write to you in your capacity as head of state and as Commander-in-Chief of the Army, Navy and Air Force.

“These steps could have been taken at any time in the past eleven years. Please do not leave it any longer.”

The duke’s is Colonel of the Grenadier Guards, one of the oldest and most emblematic regiments in the British Army.

His other British honorary military titles are: Honorary air commodore of RAF Lossiemouth; Colonel-in-chief of the Royal Irish Regiment; Colonel-in-chief of the Small Arms School Corps; Commodore-in-Chief of the Fleet Air Arm; Royal colonel of the Royal Highland Fusiliers; Deputy colonel-in-chief of The Royal Lancers (Queen Elizabeths’ Own); and Royal colonel of the Royal Regiment of Scotland.

In the letter, the veterans spoke of their own service in the military.

“All of us have served our country and are proud to have done so. For that reason, we are particularly upset and angry that Prince Andrew remains a member of the armed forces and continues to hold military titles, positions and ranks, including that of Vice Admiral of the Royal Navy.”

They added: “Were this any other senior military officer it is inconceivable that he would still be in post.

“Officers of the British armed forces must adhere to the very highest standards of probity, honesty and honourable conduct.

“These are standards which Prince Andrew has fallen well short of.

“It is hard not to see, when senior officers are reportedly describing him as ‘toxic’, that he has brought the services he is associated with into disrepute.

“We are therefore asking that you take immediate steps to strip Prince Andrew of all his military ranks and titles and, if necessary, that he be dishonourably discharged.”

Graham Smith of Republic, who helped coordinate the letter, said: “There is no excuse for allowing Andrew to continue to enjoy the status and prestige of these positions.

“The Queen needs to act now and strip him of all military ranks and titles.”