Here are relevant dates and ages David 1. On 27th April 1939, Parliament passed the Military Training Act. This act introduced conscription for men aged 20 and 21 who were now required to undertake six months' military training 2. Parliament also passed legislation that protected some occupations from national service. After consulting with business leaders, the government published the Schedule of Reserved Occupations. Employers were also able to ask for individual key workers employed in one of these key occupations not to be conscripted into the armed forces. By the end of 1940 more than 200,000 men had been granted deferment at their employers' request. 3 . On 3 Sept 1939 Parliament passed the National Service (Armed Forces) Act, under which all men between 18 and 41 were made liable for conscription. It was also announced that single men would be called up before married men. The registration of all men in each age group in turn began on 21st October for those aged 20 to 23. By May 1940, registration had extended only as far as men aged 27 and did not reach those aged 40 until June 1941. 4. On 18th December 1941, the National Service Act was passed. This authorized the call up of unmarried women aged between 20 and 30. Later this was extended to married women, although pregnant women and mothers with young children were exempt from this work. 5. On 2 Mar 1943 the Bevin Boy Call up began