[3] The regiment was established in 1859, part of the widespread volunteer movement which developed in the face of potential French invasion after Felice Orsini's attack on Napoleon III was linked to Britain.

[4] The group was organised in London by Edward Sterling, an art student, and comprised various professional painters, musicians, actors, architects and others involved in creative endeavours; a profile it strove to maintain for some years.

It had been increased to twelve companies in 1900 and was formed into three sub-battalions in 1914, and recruitment was eventually restricted by recommendation from existing members of the battalion.

It particularly attracted recruits from public schools and universities; on this basis, following the outbreak of the First World War, a number of enlisted members of The Artists' Rifles were selected to be officers in other units of the 7th Division.

Casualties suffered by members of this battalion and amongst officers who had trained with The Artists' Rifles before being posted to other regiments were 2,003 killed, 3,250 wounded, 533 missing and 286 prisoners of war.

At the start of the Second World War, and during its early stages, it was the ideas and initiatives of these amateur soldiers which led to the creation of at least two units within the Special Forces and gave a particular elan to others.

Luckily the modern SAS looks safe from this danger; it is constantly experimenting with innovative techniques, many of which stem from its Territorial regiments, drawn as they are from every walk of civilian life.

[18] In the case of an invasion, this Special Air Service Group would have let themselves be bypassed and stay-behind in order to collect intelligence behind Warsaw Pact lines and conduct target acquisition, and thus try to slow the enemy's advance.

[19] Peter de la Billière, who later commanded 22 SAS and then became Director Special Forces, served as their adjutant for part of this period.

[25] Three 21 SAS soldiers were awarded Military Crosses as a result of fighting in Nad-e Ali in Helmand Province in Afghanistan in 2008.

[26] On 1 September 2014, 21 and 23 SAS were moved from United Kingdom Special Forces and placed under the command of 1st Intelligence, Surveillance and Reconnaissance Brigade.