The British army's troops and commanders will be permitted to grow beards after almost a century of having their clean-shaven chins inspected.

This regulation change won't lead to a free-for-all, though, since facial hair length and grooming will be closely regulated.

An update that permits neat growth over the Easter break was sent out in a letter to the soldiers. Its conditions state that only a fully-grown beard is permitted.

It needs to be cut off at the cheeks and neck, measuring between 2.5 and 25.5 mm in length. According to the rules, "no patchy or uneven growth" and "no exaggerated colours" are permitted.

According to The Times, the king had to give his approval before the decision could be made, and he did so on Thursday.

Beards are permitted in the Navy and the Air Force as of 2019. However, the army has upheld a stringent policy that limited the development of facial hair to situations involving health, religion, or military requirements.

When the army launched a review last year, the great majority of military members expressed a desire to amend the regulation.

According to The Times, the new strategy was revealed to soldiers in a four-minute video message. The highest-ranking non-commissioned officer in the army, Paul Carney, has been reported as saying, “Getting to an outcome has taken a bit longer than expected due to the larger number of stakeholders that were involved, including his majesty the King, our politicians and our allies. CGS [chief of the general staff] has taken account of your views and has decided the appearance policy will change, with our officers and soldiers being allowed to grow beards.”

The army has only permitted a neat moustache as regular facial hair for almost a century.

For operational purposes, such as when on secret operations or fighting in Afghanistan, soldiers were permitted to grow beards, but they were required to shave them off when they returned.

In December, Grant Shapps, the defence secretary, declared that the army's beard ban was "ridiculous" and that it was time to update.

In an interview, he said: “The armed forces get pernickety about whether people have beards or not. Nowadays people have beards. How is it that we are still struggling with recruitment and then arbitrarily saying you can’t join [if you grow a beard]. It is ridiculous. It is time to modernize,”

A spokesperson for the army stated: “Over the last few months, we’ve been conducting a review of our policy on personal appearance. An extensive audience of regular officers and soldiers, reservists, full-time reserve service staff and veterans have taken the opportunity to provide their views.

“Army leadership have reviewed the findings and the chief of the general staff has directed that the appearance policy will change, and officers and soldiers will be allowed to grow beards. We have listened to our people and acted.”