How to Find UK Companies by Postcode for Local B2B Outreach

If you're a local services business, a regional accountant, a city-specific recruiter, a Manchester web agency, your prospect list lives or dies on postcode-level filtering. "All UK companies in our SIC code" is too broad. "Companies within 30 miles of our office" is what you actually want. Here's how to do that on Companies House data.

Why postcode filtering is harder than it looks

Companies House publishes the registered office address for every UK limited company, including the postcode. So in theory, filtering by postcode is trivial. In practice there are three gotchas:

1. Registered office ≠ trading address

Many small companies use their accountant's address or a virtual office as the registered office. So "companies registered at PO Box 1234, Manchester" includes a lot of businesses that don't actually trade in Manchester. For high-precision local prospecting, you usually want to *cross-check* with the company's website (which often has a real address) or with directors' service addresses.

2. Postcodes have multiple useful levels

UK postcodes are hierarchical:

• Area (1–2 letters): `SE`, `M`, `BT`, covers a region
• District (area + 1–2 digits): `SE1`, `M1`, `BT1`, covers a town or city section
• Sector (district + space + 1 digit): `SE1 7`, covers a few streets
• Full postcode: `SE1 7TJ`, covers a building

For local prospecting, postcode area (SE, M, etc.) is usually too broad and full postcode is usually too narrow. The sweet spot is postcode district, "SE1, SE2, SE3, SE4..." for a south-east London accountant.

3. SIC + postcode combined is the magic filter

A list of "all companies in SE1" is unwieldy. A list of "construction companies in SE1, SE2, SE3" is a workable cold-call queue. See our SIC code guide for the right SIC clusters by sector.

Doing it on Companies House data

The official Companies House search supports postcode in the search box but not as a structured filter, you can't say "give me everything in SE1 between 50 and 250 employees." For that you need either the bulk data files or a tool that's already done the filtering work.

If you want to DIY:

1. Download the monthly Companies House bulk file (~1.5GB CSV). 2. Load into Postgres / BigQuery. 3. Run `SELECT * FROM companies WHERE address_postcode LIKE 'SE1%' AND sic_codes && ARRAY['41201', '41202'] AND status = 'active'`. 4. Hand-enrich the output.

If you want a tool, Leadistry's postcode filter lets you pick any combination of areas, districts, or sectors and filter by SIC codes, incorporation date, no-website flag, and active charges all in the same search. List builds in 30 seconds.

Postcode-area cheat sheet

UK B2B services often map to specific postcode areas. A few common ones:

• EC, WC, E, N, NW, SW, W, SE, NE, S, EE, London (with E being east, etc.)
• B, Birmingham
• M, Manchester
• L, Liverpool
• LS, Leeds
• G, Glasgow
• EH, Edinburgh
• CF, Cardiff
• BT, Belfast (Northern Ireland)

For a sales rep covering "the North", the typical cluster is M, L, LS, S (Sheffield), HU (Hull), HD (Huddersfield), BB (Blackburn), PR (Preston). For "the South West", BS (Bristol), BA (Bath), TA (Taunton), EX (Exeter), PL (Plymouth), TQ (Torquay).

Common mistakes

• Filtering on registered office only, picks up a lot of accountant addresses. Cross-reference with website addresses where possible.
• Going too narrow, "SE1 7" gives you 200 companies, half of them shell companies. Postcode-district level is usually the right grain.
• Ignoring postcode plus SIC, postcode alone is still a cold-call list of 50, 000+ companies. Always combine with industry filters.

If local prospecting is your main use case, Leadistry's postcode + SIC + age filters cover the common patterns out of the box. Free trial is 6 leads, no card required.