This number, prefixed by the actual car model series designation, is stamped on a plate attached to the bonnet lock platform.

Prefix Group 1:

CodeModel
AAustin
GMG
MMorris
RRiley
VVanden Plas
WWolseley

Prefix Group 2:

CodeEngine type
AA Series (1098 - 1275cc)

Prefix Group 3:

CodeBody type
S4 door saloon
2S2 door saloon
2W2 door dual purpose
4DGrand Tourer (GT)

Prefix Group 4:

Series of Model (used to record major change) i.e. 1, 2, 3 etc.)

Prefix Group 5:

Used to denote car is different to standard right-hand drive

CodeItem
LLeft hand drive
DDeluxe
SSuper deluxe

Example:

M-A-S-1-101, which denotes this as Morris, A series engine (1098 – 1275cc), 4 door saloon, Series 1, with 101 being the cars unique number.