Question: The Cierva C.8 was built by Juan de la Cierva in association with a company founded in what year?

Context paragraphs:
Cierva C.19: The Cierva C.19 was a 1930s British two-seat autogyro, designed by Spanish engineer Juan de la Cierva.  It was built by Avro as the Avro Type 620.  It proved to be the most successful and widely produced of the early de la Cierva designs.

Cierva C.4: The Cierva C.4 was an experimental autogyro built by Juan de la Cierva in Spain in 1922 which early the following year became the first autogyro to fly successfully.  The failures of De la Cierva's previous designs, the C.2 and C.3, had led him to understand that he needed to overcome the problem of dissymmetry of lift in order to get an autogyro to fly without rolling over.  He noted that the problems that he was experiencing with his full-size aircraft were not found in the models that he had successfully flown, and considered the difference between the full-size and small-scale rotors.  De la Cierva noted that the rotors used on his model were made of bamboo, and were thus far more flexible than the ones on his full-size aircraft.  While attending an opera he realized that the flexibility reduced the moments acting on the hub and eliminated instability.  Trained as a civil engineer, Cierva was aware that an otherwise cantilever structure hinged to its attachment point also generated no moment, and he designed a rotor the blades of which were mounted to the hub through hinges to permit their vertical oscillation.

Cierva C.30: The Cierva C.30 was an autogyro designed by Juan de la Cierva and built under licence from the Cierva Autogiro Company by A V Roe & Co Ltd (Avro), Lioré-et-Olivier and Focke-Wulf.

Cierva C.8: The Cierva C.8 was an experimental autogyro built by Juan de la Cierva in England in 1926 in association with Avro.  Like Cierva's earlier autogyros, the C.8s were based on existing fixed-wing aircraft fuselages – in this case, the Avro 552.

Cierva C.3: The Cierva C.3 was an experimental autogyro built by Juan de la Cierva in Spain in 1921.  It was based on the fuselage of a Sommer monoplane, and was actually completed and tested before that aircraft.  The C.3 utilised a single, three-bladed rotor in place of the coaxial double rotor tested on the C.1.  A few short hops were achieved in testing and Cierva noted a tendency for the machine to want to roll over, thus alerting him to the problem of dissymmetry of lift that he would have to overcome in order to build a successful rotary-wing aircraft.  The C.3 was damaged and rebuilt four times before being abandoned without having flown, la Cierva returning to work on the C.2.

Avro: Avro was a British aircraft manufacturer founded in 1910 whose designs include the Avro 504 used as a trainer in the First World War, the Avro Lancaster, one of the pre-eminent bombers of the Second World War, and the delta wing Avro Vulcan, a stalwart of the Cold War.

Juan de la Cierva: Juan de la Cierva y Codorníu, 1st Count of De La Cierva (] ; 21 September 1895 in Murcia, Spain – 9 December 1936 in Croydon, United Kingdom) was a Spanish civil engineer, pilot and aeronautical engineer.  His most famous accomplishment was the invention in 1920 of the "Autogiro", a single-rotor type of aircraft that came to be called autogyro in the English language.  In 1923, after four years of experimentation, De la Cierva developed the articulated rotor, which resulted in the world's first successful flight of a stable rotary-wing aircraft, with his C.4 prototype.

Cierva C.6: The Cierva C.6 was the sixth autogyro designed by engineer Juan de la Cierva, and the first one to travel a "major" distance.  Cierva, the engineer responsible for the invention of the autogyro, had spent all his funds on the research and creation of his first five prototypes. Therefore, in 1923, he turned to the Cuatro Vientos Aerodynamics Laboratory chief, Commander Emilio Herrera, who succeeded in persuading General Francisco Echagüe, the director of the Military Aviation Aeronautics Department, to take over the second stage in the research and development of Cierva's autogyros.

Cierva C.2: The Cierva C.2 was an experimental autogyro built by Juan de la Cierva in Spain in 1921-22.  Following the failure of the C.1 the previous year, la Cierva started again from scratch, this time taking the fuselage from a Hanriot biplane and adding a five-bladed single rotor to it.  Work was interrupted when Cierva ran out of funds, and the machine was not actually completed until 1922, after his next design, the C.3 had already been built and tested.  Attempts to fly the aircraft resulted in repeated crashes, and the machine was rebuilt nine times before being finally abandoned.

Cierva C.1: The Cierva C.1 was an experimental autogyro built by Juan de la Cierva in Spain in 1920, the forerunner of his successful series of autogyros.  The C.1 was created by taking the fuselage from a Deperdussin fixed-wing aircraft and mounting two rotors shaft above it.  This shaft carried two coaxial contra-rotating rotors, and atop it a fin for increased lateral stability.  When tested, the C.1 refused to take off, which Cierva attributed to interference between the two sets of rotors leading to each set autorotating at a different speed.  He considered the possibility of mechanically linking the rotors, but dismissed the idea on the grounds of weight and complexity, and his subsequent efforts would all feature single main rotors.  Despite its failure to fly, the C.1 demonstrated the principle of autorotation in a full-sized aircraft for the first time, as it was taxied around the ground.

Supporting paragraphs: Cierva C.8 Avro
Answer: 1910