Initially those who joined the British Commandos kept their parent regimental headdress and cap badges. In 1941, No. 1 Commando had no fewer than 79 different cap badges and many different forms of headdress. "Thus a motley collection of caps, Tam o' Shanters, bonnets, forage caps, caps 'fore and aft', berets, peaked KD caps, etc., appeared on the Commando parades," says Captain Oakley, "the forest being a veritable RSM’s nightmare!"[
No. 2 Commando and No. 9 Commando faced with the same problem had adopted the Tam o' Shanter, but, as a traditional Scottish headdress, this was not considered suitable for what was a British unit. After some discussion it was agreed that if No. 1 Commando was to adopt a uniformed headdress then the beret, which had been worn by the Tank Regiment since the First World War (and had recently been adopted by the Parachute Regiment), would meet the requirements: it had no British regional affinity, it was difficult to wear improperly, and it could be easily stowed away without damage (when for example tin hats were in use).
Having decided on the headdress, the next question to be resolved was the colour. The shoulder insignia of No. 1 Commando had been designed by the Richmond Herald at the College of Arms. It incorporated three colours in its design of a green salamander going through fire: red, yellow and green. Green was chosen as the most suitable.[A Scottish firm of tam-o-shanter makers in Irvine (Ayrshire) was chosen to design and manufacture the beret.
Once the design was agreed, Brigadier Robert Laycock was approached by No. 1 Commando to seek his permission to wear it. He had been pondering on what the commandos should use for their headdress, and welcomed the green beret as a chance to introduce it as standard for all commando formations, with No. 1 Commando being the first to don them.
The proposal that the commandos should start wearing green beret as their official headdress was submitted to the Chief of Combined Operations and forwarded by Lord Mountbatten to the Under-Secretary of State for War. Approval was granted and in October 1942 the first green berets were issued to the Royal Marines.