Industry codes (SIC)
You know the sectors you sell into, whether as SIC codes already or just as a list of industries. SIC is the official coding the government uses for every company and business count, so it is how you filter national data down to your market.
UK Business Counts & Business Demography
The industries you sell into — INDUSTRY_CODE is 5-digit SIC 2007 — the same coding the UK Company Register uses, so the two line up after string normalisation
Gender Pay Gap Reports
Industry codes (SIC) — A multi-value field — split the cell before joining to the SIC hierarchy