The Hawker Siddeley Andover (HS 780) is a twin engine transport aircraft developed from the HS 748 airliner. It was named after the Avro Andover, a biplane transport aircraft used by the Royal Air Force between the wars, and RAF Andover where trials were partly carried out.

Designed to deliver cargo and evacuate casualties in a European-war scenario, the Andover was notable for its short field operating characteristics and its kneeling undercarriage system. The Andover C1 was flown for the first time on 9th July 1965. The first four examples were delivered to the Aircraft and Armament Experimental Establishment (A&AEE) Boscombe Down in Wiltshire for acceptance trials.

The Royal Air Force received its first aircraft when number 46 Sqn at RAF Abingdon received its first aircraft during December, 1966. This was closely followed by number 52 Sqn at RAF Seletar (Far East) which received an additional six aircraft during December 1966. Number 84 Sqn at RAF Sharjah (Middle East) was next in line when they received their aircraft during 1967. A total of thirty one Andover C1 aircraft were delivered to the RAF.

The Andover CC2 was designed as a VIP transport variant of the HS 748 airliner and six examples were delivered to the RAF. Initially these were delivered to number 21 Sqn at RAF Khormasksar in Aden, but these were soon passed on to number 32 Sqn, which had recently been reformed at RAF Northolt. These aircraft performed in the VIP flight role for over 18 years before being sold off on the civil market.

Other lesser known RAF users of the Andover were 51 Sqn along with the Electronic Warfare Experimental & Training Unit (EWE&TU) both based at RAF Wyton; 60 Sqn at RAFG Wildenwrath; 115 Sqn at RAF Brize Norton which flew the E3 variant in the radio and airfield aids calibration role; 242 OCU at RAF Thorney Island and last but not least the Royal Flight which operated the CC2 model.

The Andover made a suitable platform for experimental trials and saw service with the Royal Aircraft Establishment and the Empire Test Pilots School. Three aircraft are currently operational at Boscombe Down in Wiltshire. The ETPS uses XS606 while QinetiQ (previously A&AEE) operates XS596 and XS646. The former aircraft is used to conduct Open Skies verification flights. The Treaty on Open Skies was agreed in Helsinki during 1992 at the end of the Cold War and allows each side over-flight facilities of their military installations.

Ten former RAF Andover aircraft later saw service with the Royal New Zealand Air Force during 1976.