An improved version, "Blue Vesta", was developed as part of the Operational Requirement F.155 project but ended when that project was canceled in 1957. Some portions of the Blue Vesta design were then incorporated into another concept, "Red Top". Seeking improvements over Firestreak, this entered service keeping its code name, as the Hawker Siddeley Red Top. Red Top replaced Firestreak in many roles but could not be carried on early versions of the Lightning, and so Firestreak remained in service until 1988, when the last RAF Lightnings retired.