The Type 525 was a late development of the Type 508 of which three examples had been ordered from Supermarine in November 1947 to Air Ministry specification N.9/47. The Type 508s were to be development aircraft for a carrier-borne interceptor, reconnaissance and low-level nuclear strike aircraft to be built later by Supermarine to specification N.113D and which became the Type 544 which entered service as the Scimitar