 As the program continued, it was clear the aircraft would not be ready by that date, and attention turned to interim designs that could be in service by the late 1950s to cover this period.At first, consideration was given to a "thin-wing" version of the Gloster Javelin that would provide moderate supersonic performance, along with the extremely high performance but short range Saunders-Roe SR.177.In April 1956, the UK's Air Council recommended a purchase of 144 Arrows to fill the role of the thin-wing Javelin.