MG Rover V8 ID Location Places

I recently noticed a metal tag in the boot compartment floor with a number stamped on it. Out of curiosity i wondered what it was for.

Body Number Tag

The number / code stamped onto the label is of the format S RJ4 2xxxx3. After some help from the MG and 75 forums it was suggested that this was the Body Number and confirmed when I found the information below.