Building 50 At Thornton Aero Engine Research Laboratory

Aviation fuel research laboratory and offices built in 1940–41 by Sir Alan Cobham and the architects Burnet, Tait and Lorne. The building is constructed of brick with cast concrete dressings and adopts a simplified International Modern style. It has a U-shaped plan with a single storey and a central octagonal tower to the front range, with a flat roof.

The building is arranged around a central corridor flanked by offices, workrooms and a conference room in the front range. The rear wings contain central corridors flanked by laboratories and test beds.

The exterior features large casement windows to all elevations, divided by horizontal and vertical glazing bars. Cast concrete sill and lintel bands run across the facades, with a parapet at the roofline. The front range is linear with a central tower as its focal point. The entrance to the tower is raised and accessed by a short wide staircase with low flanking brick walls and concrete copings. The tower has two slender windows to each of its angled flanking faces with concrete surrounds. A concrete surround frames the tower's doorway and continues up the face to just below the parapet, incorporating a paired window at first-floor level (with one vertical and two horizontal glazing bars) and a roundel window above with similar glazing bars. Carved reliefs of mid-20th-century aircraft are positioned beneath the roundel window, and a bronze cast of the original Shell logo sits above the entrance. The main double doors are timber and partially glazed, recessed within an entrance porch. Secondary doors open from the left and right side elevations. Extractor flues rise from the right side elevation where engine test bed rooms are located. Small extensions to the rear wings date from the mid to late 1940s and feature plain casements and doors. Access to the basement plant room is gained via an external staircase to the rear yard. Some window openings have been altered: one casement at the southwest end of the left side elevation has been bricked up, and one at the southwest end of the right side elevation has been shortened with replaced glazing.

The interior retains original doors throughout. The conference room at the front left end has panelled walls, doors and built-in cabinets made from various woods including Australian black bear, Indian silver grey and African mahogany. The front range contains plain offices and workrooms. The rear wings retain their original floor plan for laboratories and test beds, though 1970s equipment has been installed; test rigs have since been removed but their floor positioning remains evident. The tower entrance hall features a coloured patterned floor incorporating a star design and a vaulted ceiling lit by Diocletian windows with Modern style glazing, topped by a decorative light fixture (the light itself has been removed). Stone tile dado and door surrounds line the front and rear doors. Double doors to the rear lead into the main corridor, above which sits a decorative plaster roundel that originally contained a clock (now removed). Built-in display cabinets are present, one with a bronze cast of the original Shell logo above. A door in the front left wall provides access to a cast-iron spiral staircase that leads to the water tank room above and the roof.

Building 50 was the first of four laboratories constructed to form Shell's Thornton Research Centre. During the 1930s, rapid advances in aero-engine design prompted Shell to recognise the need for detailed research to keep aviation fuel and oil development in pace with engine technology. In 1939, Shell decided a specialist aero-engine laboratory should be built in Britain, and the site at Thornton was selected for its proximity to the Stanlow oil refinery (established 1922), since the laboratory would also evaluate crude oil as a potential source of aviation fuel. Following the outbreak of the Second World War in September 1939, the project became urgent, and construction of the Aero-Engine Laboratory (now known as Building 50) commenced in spring 1940. The building was completed in 1941 at a cost of £128,930; until completion, scientists used temporary accommodation on site. Two further laboratory buildings were constructed later. During the war years, Building 50 was used to test and develop improved fuels and lubricants for the RAF. Because the research conducted at Building 50 was considered vital to the war effort and the future of aviation, the building operated continuously—24 hours a day, seven days a week—and some scientists were required to work 24-hour shifts. Many lived on the premises in makeshift beds as a result. Originally, Building 50 was flanked by two detached buildings, numbered 51 and 48, which were connected to Building 50 by low curved walls at the front; both were demolished in the late 1970s, along with detached workshops to the rear of Building 50. In April 1942, the Ministry Committee took charge of the laboratory's work programme whilst Shell managed the building, enabling further recruitment of expert staff and expansion of facilities. This arrangement lasted throughout the war until 1946, when full control returned to Shell. During this period, Building 50 was used to test fuel for Merlin engines fitted to Spitfires, Allison engines used in Mustangs, and Lancaster Bombers. Later in the 20th century, Building 50 tested the fuels, lubricants and greases for Concorde and provided improvements to the aircraft's fuel system before its first flight. The building ceased use in the late 20th century when laboratory and office work was relocated to more modern buildings on the Thornton site.