What is a CON29M, and what makes Martello’s different?

If you work in property or land within the coalfield areas, the CON29M Report is non negotiable. It is the official coal mining search, designed to identify whether past, present or future coal mining could affect the transaction of buying and selling property and land today.

CON29M began as the Law Society’s way to ask a single, consistent question:

Early versions of the form were text heavy and hard to apply. As Coal Authority (now Mining Remediation Authority) records were digitised, the search evolved into map led, property specific assessment that could pinpoint mine entries, shallow workings and a property’s subsidence history. For nearly two decades the form remained largely unchanged until 2018, when the Law Society permitted approved private producers to issue the official form. With the Coal Authority database available under licence, this drove competition, innovation and a step change in report quality.

Data was no longer only reported. It was interpreted with clearer actions and flags on which properties were at risk of subsidence, damage or loss of value associated with coal mining.

And yet many teams tell us the same thing: The report has flagged a risk, but it has not enabled my client to make a decision.

To understand the origin of that concern, it helps to know what the modern form actually asks.

Each question is a standard query to the Coal Authority database. For example, does the database hold a record of a mine shaft within twenty metres of this property. Historically the answer was provided as a factual, non interpreted reply. Since 2018, good CON29M reports enhance this with the follow on assessment. If there is a shaft within twenty metres, is there a risk to the property, and what should be done next.

This additional interpretation is critical, and it is not just about mine entries. Several coal mining features require a clear risk assessment so that all parties in a transaction can make informed decisions.

It is also important to remember that a CON29M is not an environmental report. An environmental screen may flag flooding or contamination, but the CON29M focuses on coal mining risk and uses the most authoritative mining records available.

Different tools, different datasets, different questions. An environmental PASS on ground stability often reflects natural hazards within the scope of the available data. A CON29M may flag additional actions when mining risk is present because it is answering a more specific question about coal mining-related hazards.

This is the gap we set out to close. A mining search should not stop at saying a feature exists. It should explain how that feature could affect this specific site and what to do next. In the Martello Official CON29M we assess the data & make it clearly visible within the report, for the first time so all parties within the transaction have clarity.

We then set out, in plain English, the likely risks & the practical consequence for the transaction, with the recommended next steps. The result is a report you can lift straight into client, lender and insurer conversations without another a back & forth on clarification.

The CON29M is there to answer a clear question. Could coal mining affect this property. Modern reports should not only confirm the presence of features. They should explain the mechanism, the consequence and the next step. That is the standard we hold ourselves to with our Official CON29M.

If your environmental report passes but the CON29M raises questions, treat that as useful signal. Different tools answer different questions. Use the mining report to brief clients, lenders and insurers with confidence.

Next week we will dive into mine entries, covering why lenders often red flag them, what really drives risk, and the myths and truths every conveyancer should know.