Number codes written on death registrations

I saw a question in another (not family history) forum about a code number written on a death registration: next to "Formerly a locomotive engine driver" was written "512/1". On checking the images I've got I found a couple of examples I'd not noticed. I'm talking about the handwritten copy sheets sent from the local registration offices to the GRO itself: the ones we see in the PDFs and online images we buy. The numbers look like the occupation codes written onto the 1911 and 1921 census sheets. The examples I have are from 1910-11, and not from all of them, suggesting a sample was selected for whatever purpose this served.

Here are my two, to show what I mean:



I've found what the numbers mean - they are occupation codes (similar to the 1911 census ones) and the ones under the age or sex are cause of death codes (probably from ICD-2). I can guess what might be going on here, but does anyone know what the purpose of this coding exercise was?

 

Shows statistical analysis being done at GRO.....just as gets done today.

Nowadays registrars collect quite a lot of extra information when registering births/deaths, such as if parents are married, date of marriage, number of children born to a mother, details of employment beyond just the job title, and more, which doesn't appear on the register entry but gets sent to the ONS ( Office for National Statistics) and they use it for reports & forecasts on population patterns/trends etc.