National Registration Act 1939
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 the Republic of 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 buff cards were issued to children under 16 but did not carry a class code.
Regards
Malky