other directors agreed to sell to Vickers in 1928. Vickers paid £390,000 and renamed it as Supermarine Aviation Works (Vickers) Ltd. Subsequently, in December 1938, following both Air Ministry's and the Vickers board's concerns over delays to the Spitfire and Wellington manufacturing programmes, all Vickers-Armstrongs aviation interests were reorganised to become Vickers-Armstrongs (Aircraft) Ltd, with both Vickers and Supermarine now under a single management team. Both subsidiaries were then formally wound up, although Supermarine continued to design, build and trade under its own name. The phrase Vickers Supermarine was applied to the aircraft. Despite selling his shares to Vickers-Armstrongs, Bird stayed on as managing director of Supermarine while Mitchell continued as chief designer. He had signed a 10-year employment contract in 1923, that included a clause that said, if he left Supermarine he could not work for any other competitor without the directors written consent. While Supermarine was extremely profitable McLean and his management team were of the opinion that as well as wages being higher than at Vickers, it was also not being run efficiently, had poor record keeping, stock control, and was poorly equipped to build all-metal aircraft, with the ratio of unskilled to skilled labour at 1:3 compared with Vickers' 3:1. They therefore saw numerous opportunities to improve the profitability. One measure Vickers undertook was to send their experienced engineer Barnes Wallis to overhaul the work practices in the design department. He arrived while Mitchell was away on his 1929 Christmas holidays and after installing himself in Mitchell's office began to make changes. Mitchell returned in the New Year, expressed his outrage at Wallis's presumption and immediately moved him to a disused loft in a remote corner of the Woolston works with orders to his staff not to make the interloper comfortable. Wallis eventually complained to McLean, who raised it with the board of Vickers-Armstrongs. Faced with Mitchell's threat to resign if Wallis remained, they backed down and Wallis was recalled back to Weybridge. Shortly after Wallis's departure Major Harold Payn, an engineer from Vickers design department was appointed by Vickers as Mitchell's deputy. A former pilot with experience from World War I, as well as testing aircraft despite little design experience it was hoped that he would be more diplomatic in bringing Supermarine's design office into agreement with Vickers work practices. That said the parent company provided the combined Vickers (Aviation) Ltd with £250,000 in 1929