In 1936, General Giffard LeQuesne Martel, a pioneer in tank design who had published works on armoured warfare and pioneered the lightly armoured "tankette" concept to enhance infantry mobility, became Assistant Director of Mechanization at the War Office. Later that year, Martel had watched Soviet tanks at the Red Army's autumn manoeuvres including the BT tank, which they had developed from Christie's work. He urged the adoption of a tank that would use the suspension system and also follow the Christie practice of using a lightweight aircraft engine such as the Liberty L-12 engine or a Napier Lion. The government authorised purchase and licensing of a Christie design via the Nuffield Organization.