Work on GOR.339 continued, with a deadline for submissions on 31 January 1958. Many proposals were entered; English Electric teamed up with Short Brothers and submitted its P.17A along with the Shorts' P.17D, a vertical-lift platform that would give the P.17 a VTOL capability; designs were also received from Avro, Blackburn (the NA.39), de Havilland, Fairey, Hawker and Vickers-Armstrongs. The Air Ministry eventually selected the EE P.17A and the Vickers-Armstrongs Type 571 for further consideration. The Ministry was particularly impressed with the Vickers submission, which included not only the aircraft design, but a "total systems concept" outlining all the avionics, support facilities and logistics needed to maintain the aircraft in the field. Official opinions of English Electric's management found it decidedly lacking in comparison to Vickers, but the combination of the two was felt by officialdom to be a useful marriage and accordingly the development contract was awarded to Vickers, with English Electric as sub-contractor.