Every UK incorporated entity receives an eight‑character company number. The number stays fixed for the life of the company. Name changes do not affect it. Moving the registered office does not either. For diligence work this identifier is far more reliable than the company name, which can change several times within a decade.
Companies House runs one of the most open corporate registers among major jurisdictions. Core records sit in the public domain and anyone can search them without paying. The dataset includes director appointments and the People with Significant Control (PSC) register introduced by the Small Business, Enterprise and Employment Act 2015. Auditors rely on it. Journalists read it. Compliance teams check it daily. OpenRegistry surfaces the same upstream records through MCP so an AI assistant can call them inside an existing workflow.
What the registry actually returns
A Companies House profile contains a set of fields commonly used during issuer checks or counterparty screening.
company_number is the primary identifier. UK numbers also hint at the entity form. The prefix SC marks a Scottish company. OC appears on LLP registrations.
date_of_creation stores the incorporation date recorded by Companies House. For older issuers this often becomes the earliest trustworthy timestamp in the public file.
registered_office_address gives the legal address for service. It does not confirm where business activity occurs. It does fix the jurisdiction where statutory filings must arrive.
sic_codes contains the UK Standard Industrial Classification codes reported in the latest confirmation statement. Companies self‑declare these codes and they tend to be broad. Even so, they help when filtering large sets of entities.
Officer data comes from the appointments register. Each entry includes fields such as officer_role and appointed_on. Some records also show resigned_on. Patterns in these dates can reveal when management shifted.
Ownership disclosure appears in the PSC register. Companies must report individuals or legal entities controlling more than 25 percent of shares or voting rights. Typical PSC entries include natures_of_control, notified_on, and sometimes ceased_on.
Filing history exposes the timeline of submissions made to the registry. Each item carries metadata such as category, type, and date. When Companies House has published a document, the entry also carries a link to the PDF.
OpenRegistry returns these fields exactly as Companies House publishes them inside jurisdiction_data. No normalisation. No interpretation layer. If the registry records a PSC description as “ownership of shares 25 to 50 percent”, that wording appears unchanged in the response.
Gaps you will still hit
The UK corporate register is transparent. Complete is another matter.
There is no comprehensive shareholder register in the public dataset. Only PSC disclosures appear. Shareholdings below the 25 percent threshold stay invisible unless they surface in filings such as allotment returns.
Companies House also does not publish Ultimate Beneficial Owner determinations in the sense used by banks under AMLD frameworks. The PSC regime is a disclosure mechanism. It records statements made by companies. It does not attempt to calculate a verified ownership graph.
Accounts data introduces another limitation. Many small firms file abridged or micro‑entity accounts under the Companies Act 2006. Balance sheets normally appear. Detailed profit figures may not.
Director and PSC identity checks are also in transition. The Economic Crime and Corporate Transparency Act 2023 introduces verification requirements. Rollout is still underway as of 2026. Older records therefore contain nominee directors and service provider addresses that reflect earlier filing rules.
Querying Companies House through MCP
Once OpenRegistry is connected to an assistant, most workflows begin with a search.
Example tool call:
search_companies({
"jurisdiction": "GB",
"query": "Revolut Ltd"
})
The response lists matching entities and returns the company_number. That identifier opens the rest of the record.
Company profile lookup:
get_company_profile({
"jurisdiction": "GB",
"company_number": "08804411"
})
Officer information uses its own endpoint.
get_officers({
"jurisdiction": "GB",
"company_number": "08804411"
})
PSC records require a separate call because the legal register sits apart from the officer register.
get_persons_with_significant_control({
"jurisdiction": "GB",
"company_number": "08804411"
})
When a filing document matters for diligence, request it directly from the entry in the filing history.
fetch_document({
"jurisdiction": "GB",
"document_id": "0001234567"
})
The returned file is the original PDF stored by Companies House. That detail matters during audits. The document itself forms the legal record rather than a reformatted database row.
Why finance teams still read the register
Cross‑border diligence often starts with a single UK company somewhere in a group structure. The confirmation statement lists the declared SIC activity. Officer appointments show when leadership changed. PSC disclosures may reveal a controlling shareholder appearing before a financing round.
Small clues accumulate. A Cayman parent connected through PSC filings becomes visible. A newly appointed director signals a governance shift. Dates help reconstruct the sequence.
Aggregator datasets hold similar information, yet many depend on periodic snapshots of registry data. When a director resigns or a new charge is filed, the official register publishes it first. Pulling the filing history directly avoids stale exports.
AI assistants help because the pattern repeats. Search for the company. Retrieve the profile. Inspect officer records. Review PSC entries. Download the latest accounts. Each step maps to a registry call.
OpenRegistry exposes Companies House along with 27 national company registers through a single MCP interface. An assistant can follow ownership trails across borders without switching sources. Details and the MCP endpoint are documented at https://openregistry.sophymarine.com.
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