In 1964 fatigue was discovered due to the increased air turbulence in low level flying and led to the type's premature retirement. Vic Flintham observed that: "There is a fine irony to the situation, for Vickers had produced the Type 673 B Mk 2 version designed as a fast, low-level pathfinder... The Air Ministry was not interested..." The Valiant was Vickers' last purpose-built military aircraft. It was followed by the Vanguard, a passenger turboprop designed in 1959, and the Vickers VC10, a jet passenger aircraft in 1962, also used as a military transport and tanker by the RAF.