mass evacuation and also the wartime need for complete manpower control and planning in order to maximise the efficiency of the war economy. The likelihood of rationing (introduced from January 1940 onwards). Population statistics. As the last census had been held in 1931, there was little accurate data on which to base vital planning decisions. The National Register was in fact an instant census and the National Registration Act closely resembles the Census Act 1920 in many ways. The register was also used to support the administration of rationing after this was introduced in January 1940. 1943 (Blue) Identity Card The more commonly found green version of the identity card (not the image shown) was issued in 1943 for adults. Until then, adult identity cards had been a buff (an off yellow) coloured card, not the same colour as children's cards, which was a manila coloured (brown) card. Government officials had green ID cards with endorsements, and a photograph, whilst those in the armed services, or temporary displaced persons were issued with a 'Blue' version of the identification cards. Children under 16 were issued with Identity Cards, but they were to be kept by their parents. Identification was necessary if families were separated from one another or their house was bombed, and if people were injured or killed. The sections in the card showing the change in address were important, as many people moved several times during the war. Class codes Class Codes were used for administration and electoral purposes. Cards were marked A, B, C, N or V. A: Aged over 21 B: Aged between 16 and 21 Additionally, all class code 'B' cards were followed by three numbers. The first two indicated the year in which the holder was born whilst the third indicated which quarter of the year the holder was born in. For example, B. 252 would show that the holder was born in the second quarter of 1925 and would also indicate to a polling clerk that the holder would attain adult status in the second quarter of 1946 (i.e. reach the age of 21). C: Appeared on yellow cards issued to workers from 'Eire' (Ireland) who were conditionally admitted to Great Britain. N: Cards re-issued under an altered name. V: Placed on yellow cards issued to people over 16 arriving in this country who declared that they were usually resident outside the UK. Temporary