00 = Unitary authority
09 = Bedfordshire
11 = Buckinghamshire
12 = Cambridgeshire
13 = Cheshire
15 = Cornwall and Isles of Scilly
16 = Cumbria
17 = Derbyshire
18 = Devon
19 = Dorset
20 = Durham
21 = East Sussex
22 = Essex
23 = Gloucestershire
24 = Hampshire
26 = Hertfordshire
29 = Kent
30 = Lancashire
31 = Leicestershire
32 = Lincolnshire
33 = Norfolk
34 = Northamptonshire
35 = Northumberland
36 = North Yorkshire
37 = Nottinghamshire
38 = Oxfordshire
39 = Shropshire
40 = Somerset
41 = Staffordshire
42 = Suffolk
43 = Surrey
44 = Warwickshire
45 = West Sussex
46 = Wiltshire
47 = Worcestershire

S = Scotland
U = England
W = Wales
X = Foreign (from 1990-91 onwards)
Y = Not known
Z = Northern Ireland