United Kingdom aircraft test serials

[1] They can be used for testing experimental and prototype aircraft or modifications, pre-delivery flights for foreign customers and are sometimes referred to as "B" class markings.

[1] An initial set of markings was introduced in 1929, each company was allocated a letter to which would follow a number, sometimes with a hyphen or a gap between.

[1] Sometimes Hawker and Vickers would also add the letters PV to the markings to indicate a private venture (that is a type in development not paid for by the Air Ministry).

[1] The presentation was changed to look like a military serial for security reasons during the Second World War.

[1] Companies could allocate and re-use the identities as they liked, some ran in sequence from 1 and others used the aircraft manufacturers serial number as part of the marking, for example G-51-200 was a Britten Norman Islander with a manufacturers serial number of 200.