Their grizzly and unkempt facial hair could not be further removed from the regulation short back and sides that of the modern British Servicemen.

But in a historic exception to regulations, RAF soldiers have been given permission to grow bushy beards for tours of duty in Afghanistan.

Scottish airmen in Kandahar bear a more than passing resemblance to their wild Pashtun counterparts – complete with wavy beards and ferocious moustaches.

In what is believed to be a first for the RAF, several airmen were asked to grow their facial hair because it is considered a mark of authority in Afghanistan. The men, from RAF Lossiemouth, credited their facial hair with enabling them to command respect from the Afghanistan people.

Senior personnel also said that their presence had helped significantly to reduce the number of rocket attacks on Kandahar airfield.

Their success would come as no surprise to the leaders in the American Civil War – it is harder to find a picture of a general from the century conflict without a beard than with one. In fact, the beard was once the only universal item in every military organisation across the world.

From the time of ancient armies until recent memory, the beard was standard issue among soldiers. In modern combat, the act of shaving was set aside mainly for gentleman officers, who regularly shaved even their heads and eyebrows.

But by the time of the Second World War, armies had banned beards for reasons of uniformity, hygiene, discipline, or tactical demands – such as the proper fitting and seal of a gas mask.

The Scottish troops will be ordered to shave as soon as they return from Afghanistan. At RAF Lossiemouth, Flight Commander Kevin O’Brien said that their beards had been a talking point among village leaders in Afghanistan.

“From the start with these adoptive beards it was looked upon [by village leaders] as if we were trying to adopt their culture and respect them. From my experience, while talking to the key leaders, they would be pointing at my beard and discussing it.

“When we were being more forceful and trying to deal with incidents, if I spoke they would look back, accept I was the leader of our side of this, and pay attention.”

About 120 members of 51 Squadron RAF Regiment were deployed to Kandahar in March to carry out ground patrols at the Nato airfield, supported by 20 part-time volunteer gunners from RAF Lossiemouth’s 2622 (Highland) Squadron. The RAF said it was believed to be the first time personnel had been allowed to grow beards for an operation.