Question: What special forces unit of the British Army was founded in 1941, and was served by Sergeant Alistair Slater? 

Context paragraphs:
Cuerpo de Fuerzas Especiales: The Mexican Cuerpo de Fuerzas Especiales (Special Forces Corps) is a special forces unit of the Mexican Army.  Formerly the "GAFE" (Grupo Aeromóvil de Fuerzas Especiales | Special-Forces Airmobile Group), the SF Corps has six battalions; one is the "Fuerza especial de reaccion", a quick-response unit, and one is assigned to the Paratroopers Rifle Brigade; the motto of the SF Corps is "Todo por México" (Everything for Mexico).  Within the SF Corps, there are regular, intermediate, and veteran -service troops.  The regular-service soldiers usually operate as light infantry.  The intermediate-service soldiers (lieutenants and captains) usually are instructors.  The veteran-service soldiers of the Grupo Aeromóvil de Fuerzas Especiales del Alto Mando (GAFE High Command) handle Black-Ops missions.  Also known as the COIFE, the Special Forces Corps of the Mexican Army is equivalent to the U.S. Army Special Forces.

Special Air Service: The Special Air Service (SAS) is a special forces unit of the British Army.  The SAS was founded in 1941 as a regiment, and later reconstituted as a corps in 1950.  The unit undertakes a number of roles including covert reconnaissance, counter-terrorism, direct action and hostage rescue.

Sean Drummond: Lt. Col. Sean Drummond is the protagonist of a series of novels written by Brian Haig.  He was born in 1965.  Son of a US Army colonel (who was injured in the Vietnam War), he joined the US Army as an infantry officer and was later recruited by a special forces unit nicknamed "The Outfit", until he was injured in combat and was forced to change his career path.  He became a member of a special group of JAG lawyers (Judge Advocate General Corps), which handles cases involving members of the US special forces or the military intelligence community.  In the beginning of his career as a JAG lawyer, he worked primarily in what is known as "Black Court," (officially called SPECAT Court) where special forces members are tried without risk of exposing their missions.  He went to Georgetown Law and graduated with the second highest grade in his class.

Special Forces Regiment (Airborne): The Special Forces Regiment (Airborne) is a special forces unit of the Philippine Army and one of three specialized regiments of the Special Operations Command.  The unit is based on and continually trains with its american counterpart, the U.S. Army Special Forces (Green Berets).

Alistair Slater: Sergeant Alistair Slater, MM (25 July 1956 – 2 December 1984), was a British Army soldier who served in B Squadron, Air (7) Troop, 22 Special Air Service (SAS), who was killed on 2 December 1984 while on operations against the Provisional Irish Republican Army in Kesh, a village in County Fermanagh in Northern Ireland.

Giretsu Kuteitai: Giretsu (義烈空挺隊 , Giretsu Kūteitai ) ("Heroic Paratroopers") was an airlifted special forces unit of the Imperial Japanese Army formed from Army paratroopers, in November 1944 as a last-ditch attempt to reduce and delay Allied bombing raids on the Japanese home islands.  The "Giretsu" Special Forces unit was commanded by Lieutenant General Michio Sugahara.

1º Compañía de Comandos &quot;Iquique&quot;: The 1st Commandos Company "Iquique" ("1º Compañía de Comandos "Iquique"" in Spanish) is special forces unit under the jurisdiction of northern Chile.  The unit is part of the 2nd Armored Brigade "Cazadores" ("2º Brigada Acorzada "Cazadores"" in Spanish) of the Sixth Army Division based in the first region of the country.  The Chilean Army has been restructured into more independent armored brigades and shaped only by professional people, meaning that each squad possesses a special forces unit.

Sayeret Matkal: General Staff Reconnaissance Unit 269, more commonly known as Sayeret Matkal (Hebrew: סיירת מטכ"ל‎ , General Staff Reconnaissance Unit) is a special forces unit of the Israel Defense Forces (IDF).  First and foremost a field intelligence-gathering unit, conducting deep reconnaissance behind enemy lines to obtain strategic intelligence, Sayeret Matkal is also tasked with counter-terrorism and hostage rescue beyond Israel's borders.  The unit is modeled after the British Army's Special Air Service, taking the unit's motto "Who Dares, Wins".  The unit is the Israeli equivalent of Delta Force of the United States and to the UK's Special Air Service.  It is directly subordinate to the IDF's Directorate of Military Intelligence.

Special Operations Force (Singapore): The Special Operations Force (SOF) is the Republic's Army Special Forces composed of highly trained elite soldiers within the Singapore Armed Forces Commando Formation and an essential component of the joint special forces unit Special Operations Task Force (SOTF).  According to the Principles of Special Forces, the Republic's special forces thrive on their exceptional qualities and advanced skills, consisting highly adaptive individuals who are independent and can operate independently, and the Republic's special forces soldiers cannot be mass-produced and must be managed carefully.

Bhairavnath Battalion: The Bhairavnath Battalion is an Army Battalion in the Nepalese Army as the elite special forces unit of the Nepalese Army.  The battalion was trained by the Israeli Special Forces, IDF to fulfil a need to establish a special forces wing to modernize the army.

Supporting paragraphs: Alistair Slater Special Air Service
Answer: Special Air Service