Ladywood Works (The Offices and That Part Known As B3 Unit B Adjacent to the North, Once Occupied by Sir Frank Whittle and Power Jets Ltd.)

Ladywood Works consists of factory offices with an attached section of factory buildings now known as B3 Unit B. Built in the early 20th century, the complex is constructed of red brick with slate roofs and coped gables. The offices are two storeys high with a rendered front elevation, featuring a ten-window range at first-floor level with various windows and doors below, the cross windows being original. The factory section is single-storey with north-light roofs.

The office building contains various offices fitted with steel truss roofs. The office at the far right on the first floor, where Sir Frank Whittle worked, includes an internal window overlooking the factory interior and has since been joined with the adjacent office. The factory interior also features steel truss roofs. The part of special historic interest comprises the first two bays of north-light roof, including a section projecting forward to the left of the office building, which now has a recent corrugated metal front. The remainder of the factory was not used by Whittle's team and is not considered of special architectural or historic interest.

The Ladywood buildings were originally constructed for use as a foundry in the early 20th century by British Thomson Houston. In 1937, Sir Frank Whittle, a serving RAF member and director of Power Jets Ltd., and his team were invited to move to the vacant buildings when BTH decided that experimental work at their Rugby factory had become too dangerous. By January 1938 at the latest, Whittle's design team occupied the office building in crowded conditions, with engineers working on the stairs. Whittle's own office was positioned on the first floor at the right-hand end, overlooking the railway line, while ground-floor rooms housed the engineers' offices.

The jet engine was tested from April 1938 in a factory bay adjacent to the offices to the west, within an internal testing house now demolished. The external low factory wall adjoining the left end of the office block marks the south wall of the original test room, through which engine exhaust was vented. Only the first two bays of the factory closest to the offices were utilised by Whittle's team: the first bay served fitters for sheet-metal work and welding, while the next bay with north-light roof functioned as the machine shop by 1941.

Whittle's jet engine was installed in the Whittle/Gloster E28/39, which had its maiden flight at RAF Cranwell on 15 May 1941. The engine is now in the Science Museum, London. A version of this engine was built at Ladywood Works and shipped to the USA, where it founded the North American and subsequently the world-wide jet engine industry. Whittle always considered Ladywood Works the most important place connected with his invention, which he developed in utmost secrecy during the war years. The architectural quality of the buildings is limited, but their historical significance is immense, deriving from the world-changing events that occurred within their modest exterior.