Question: Which English actor starred in Cabin Pressure 

Context articles: Cabin Pressure (radio series)
Space suit
Anthony Head
Far Eastern Air Transport Flight 103
Roger Allam
John Finnemore (writer)
Cabin Pressure (film)
Bleed air
Cabin pressurization
Hydraulics International

Cabin Pressure is a radio sitcom written and created by John Finnemore and directed and produced by David Tyler.
 It follows the exploits of the eccentric crew of the single aeroplane owned by "MJN Air" as they are chartered to take all manner of items, people or animals across the world.
 The show stars Finnemore, Stephanie Cole, Roger Allam and Benedict Cumberbatch.
 The series was first broadcast on BBC Radio 4 in 2008.
A space suit is a garment worn to keep a human alive in the harsh environment of outer space, vacuum and temperature extremes.
 Space suits are often worn inside spacecraft as a safety precaution in case of loss of cabin pressure, and are necessary for extravehicular activity (EVA), work done outside spacecraft.
 Space suits have been worn for such work in Earth orbit, on the surface of the Moon, and en route back to Earth from the Moon.
 Modern space suits augment the basic pressure garment with a complex system of equipment and environmental systems designed to keep the wearer comfortable, and to minimize the effort required to bend the limbs, resisting a soft pressure garment's natural tendency to stiffen against the vacuum.
 A self-contained oxygen supply and environmental control system is frequently employed to allow complete freedom of movement, independent of the spacecraft.
Anthony Stewart Head (born 20 February 1954) is an English actor and musician.
 He rose to fame in the UK following his role in the Gold Blend couple television advertisements for Nescafé Gold Blend, and is known for his roles as Rupert Giles in "Buffy the Vampire Slayer", Uther Pendragon in "Merlin", the Prime Minister in "Little Britain", and as Herc Shipwright in BBC Radio 4's "Cabin Pressure".
Far East Air Transport Flight 103 (callsign FAR EASTERN 103), a Boeing 737-222, registration B-2603, departed Taipei Songshan Airport for Kaohsiung on 22 August 1981.
 The aircraft lost cabin pressure 10 minutes after takeoff and broke apart 4 minutes later.
Roger William Allam (born 26 October 1953) is an English actor, known primarily for his stage career, although he has performed in film, television and radio.
John David Finnemore (born 28 September 1977) is a British comedy writer and actor, best known for his radio sitcom "Cabin Pressure" and his radio sketch show "John Finnemore's Souvenir Programme", as well as for frequent appearances on other BBC Radio 4 comedy shows such as "The Now Show".
 Finnemore is noted for winning more Comedy.co.uk Awards than any other writer.
Cabin Pressure (also known as Hijack'd and Autopilot) is a 2002 Canadian action film.
 The made-for-television film was broadcast in 2003 and released to home media shortly after.
 "Cabin Pressure" reunited Craig Sheffer and John Pyper-Ferguson (who appeared together in the 1994 movie "Roadflower").
 The film also featured Canadian voice actor Michael Kopsa.
Bleed air produced by gas turbine engines is compressed air that is taken from the compressor stage of those engines, which is upstream of the fuel-burning sections.
 In modern airliner engines, two regulator valves (high stage and low stage) turn on and off automatically and are controlled by at least "...two air supply and cabin pressure controllers (ASCPCs) which open and close appropriate valves.
 Engine bleed air comes from the high stage or low stage engine compressor section.
 Low stage air is used during high power setting operation, and high stage air is used during descent and other low power setting operations."
 Bleed air from that system can be utilized for internal cooling of the engine, cross-starting another engine, engine and airframe anti-icing, cabin pressurization, pneumatic actuators, air-driven motors, pressurizing the hydraulic reservoir, and waste and water storage tanks.
 Some engine maintenance manuals refer to such systems as "customer bleed air".
 Bleed air is valuable in an aircraft for two properties: high temperature and high pressure (typical values are 200–250 °C and 275 kPa (40 PSI), for regulated bleed air exiting the engine pylon for use throughout the aircraft).
Cabin pressurization is a process in which conditioned air is pumped into the cabin of an aircraft or spacecraft, in order to create a safe and comfortable environment for passengers and crew flying at high altitudes.
 For aircraft, this air is usually bled off from the gas turbine engines at the compressor stage, and for spacecraft, it is carried in high-pressure, often cryogenic tanks.
 The air is cooled, humidified, and mixed with recirculated air if necessary, before it is distributed to the cabin by one or more environmental control systems.
 The cabin pressure is regulated by the outflow valve.
HII manufactures defense ground support equipment including ammunition loading systems, aircraft hydraulic system testing, aircraft cabin pressure testing, power systems, environmental control systems, military trailers, high pressure gas and liquid systems, flow measuring equipment, and logistics and support services.