 The cancellation also left the British Army without a defense system, but they had prepared for this eventuality, having had several US missile systems cancelled out from under them in the past.Before selecting the Mauler, the British Aircraft Corporation had been working on a private project known as "Sightline", and continued its development as a low priority while the Mauler program progressed.On its cancellation, Sightline was given full development funds, and entered service in 1971 as Rapier.