diff --git a/source/Development/developing_change.rst b/source/Development/developing_change.rst
index ba4646cb..31f6ab23 100644
--- a/source/Development/developing_change.rst
+++ b/source/Development/developing_change.rst
@@ -54,6 +54,7 @@ carefully:
     kgo
     diagnostics
     rose_stem
+    testdata
     testing
 
 .. important::
diff --git a/source/Development/testdata.rst b/source/Development/testdata.rst
new file mode 100644
index 00000000..8d5fd577
--- /dev/null
+++ b/source/Development/testdata.rst
@@ -0,0 +1,109 @@
+.. -----------------------------------------------------------------------------
+    (c) Crown copyright Met Office. All rights reserved.
+    The file LICENCE, distributed with this code, contains details of the terms
+    under which the code may be used.
+   -----------------------------------------------------------------------------
+
+.. _testdata:
+
+Adding Test Data
+================
+
+.. note::
+
+    This page is a placeholder for information about test data. It is not yet
+    complete and will be updated in due course.
+
+    *The instructions here are Met Office specific, other sites may manage their
+    test data differently.*
+
+.. important:: **Attribution Metadata Policy**
+
+    If the change requires a new or updated file in ``LFRIC_DATA_DIR`` then you
+    will need to work with the Information Asset Owner (IAO) to ensure that data
+    in ``LFRIC_DATA_DIR`` includes clear attribution and licence metadata.
+    Where possible, this should follow existing UM ``ANCILDIR`` conventions (`see
+    below <prerequisites-section_>`_), with ``.attribution`` and ``.license``
+    files or equivalent NetCDF **global attributes** (at least, ``references``,
+    ``license``, ``source``, and ``history``). Attribution must reflect the
+    original data source and be provided by the data creators before deployment,
+    share, or distribution.
+
+    It is treated as an **Information Asset / licensing requirement**, not just
+    a best practice.
+
+
+For UM related datasets, please Email the `MIAO team <mailto:miao@metoffice.gov.uk>`_
+to discuss the best way to share the data.
+
+.. _prerequisites-section:
+
+Prerequisites
+-------------
+
+Before adding test data, you should have a good understanding of the change you
+are making and the tests you will be adding. You should also have a good
+understanding of the codebase and the testing framework you will be using.
+
+Licenses
+~~~~~~~~
+
+All files require a licence and a record of where they have come from, both
+for legal and auditing purposes. In your request please describe where and how the
+data was generated, and the terms and conditions of its licence.
+
+Before any files can be deployed, they must be approved by an IAO and this cannot be done
+without information about the licencing terms.
+
+Metadata
+~~~~~~~~
+
+All file requirements should be recorded in or alongside the files being
+deployed.
+
+If a source file has a licence that imposes requirements on derived
+works, then any ancillary file (or an intermediate file used to generate an
+ancillary) counts as a derived work for the purposes of recording metadata.
+
+In cases where a file has been generated from multiple sources, the licences
+must be compatible with each other and it should be made clear where each
+licence/attribution/acknowledgement has come from.
+
+NetCDF Files
+^^^^^^^^^^^^
+
+NetCDF files should have the relevant metadata included in the file itself.
+The metadata should include the following information:
+
+* The licence should be in a ``license`` global attribute as per
+  `ESIP Attribute Convention for Data Discovery <https://wiki.esipfed.org/Attribute_Convention_for_Data_Discovery_1-3#Recommended>`_.
+
+* If there is a paper attribution requirement, the relevant paper(s) should be
+  cited in the ``references`` global attribute as per
+  `CF conventions <https://cfconventions.org/Data/cf-conventions/cf-conventions-1.11/cf-conventions.html#description-of-file-contents/>`_.
+
+* If there is an organisation attribution requirement, it should be in the
+  ``institution`` global attribute (again, as per CF).
+
+* If there is any other attribution requirement (e.g. for an individual), it
+  should be in the ``acknowledgement`` global attribute (again, as per ACCD).
+
+* If there are restrictions on usage (e.g. "research only"), these should be in
+  a ``restrictions`` global attribute.
+
+Other Files
+^^^^^^^^^^^
+
+* Licence should be in an accompanying plain text file with the same name as the
+  data file, but with a ``.license`` suffix.
+
+* Attribution should be in an accompanying plain text file with the same name as
+  the data file, but with a ``.attribution`` suffix.
+
+* Restrictions on usage (e.g. "research only") should be in an accompanying
+  plain text file with the same name as the data file, but with a
+  ``.restrictions`` suffix.
+
+If you have questions about the process or concerns about the provenance of the
+data you want to include, please engage with the IAO as early as possible to
+prevent delays to your change later on.