Could you please explain to me what version of the SIC codes are being used because I see that the constants.yml file that you host on GitHub does not match this:
http://resources.companieshouse.gov.uk/sic/
Why are there differences and which is correct?
Nature of business: Standard Industrial Classification (SIC) codes are the codes that we will accept for new companies and changes to existing company data. The contants.yml file also contains some legacy 4 digit SIC codes that are still held against some older companies.
Hope this helps.