diff --git a/.github/scripts/python/validate-existing-contributors/.venv/.gitkeep b/.github/scripts/python/validate-existing-contributors/.venv/.gitkeep
new file mode 100644
index 00000000..e69de29b
diff --git a/.github/scripts/python/validate-existing-contributors/Pipfile b/.github/scripts/python/validate-existing-contributors/Pipfile
new file mode 100644
index 00000000..ffe061c7
--- /dev/null
+++ b/.github/scripts/python/validate-existing-contributors/Pipfile
@@ -0,0 +1,16 @@
+[[source]]
+url = "https://pypi.org/simple"
+verify_ssl = true
+name = "pypi"
+
+[packages]
+
+[dev-packages]
+black = "==23.1.0"
+pytest = "==7.2.1"
+mypy = "==1.6.1"
+pylint = "==3.0.2"
+types-requests = "==2.31.0.10"
+
+[requires]
+python_version = "3.11"
diff --git a/.github/scripts/python/validate-existing-contributors/Pipfile.lock b/.github/scripts/python/validate-existing-contributors/Pipfile.lock
new file mode 100644
index 00000000..e31ed49f
--- /dev/null
+++ b/.github/scripts/python/validate-existing-contributors/Pipfile.lock
@@ -0,0 +1,229 @@
+{
+    "_meta": {
+        "hash": {
+            "sha256": "4dc4a5a52138e83335a5ec27a3e6fa7385d5654328e3b3dc0b33cebcf3d1bf80"
+        },
+        "pipfile-spec": 6,
+        "requires": {
+            "python_version": "3.11"
+        },
+        "sources": [
+            {
+                "name": "pypi",
+                "url": "https://pypi.org/simple",
+                "verify_ssl": true
+            }
+        ]
+    },
+    "default": {},
+    "develop": {
+        "astroid": {
+            "hashes": [
+                "sha256:4a61cf0a59097c7bb52689b0fd63717cd2a8a14dc9f1eee97b82d814881c8c91",
+                "sha256:d6e62862355f60e716164082d6b4b041d38e2a8cf1c7cd953ded5108bac8ff5c"
+            ],
+            "markers": "python_full_version >= '3.8.0'",
+            "version": "==3.0.2"
+        },
+        "attrs": {
+            "hashes": [
+                "sha256:935dc3b529c262f6cf76e50877d35a4bd3c1de194fd41f47a2b7ae8f19971f30",
+                "sha256:99b87a485a5820b23b879f04c2305b44b951b502fd64be915879d77a7e8fc6f1"
+            ],
+            "markers": "python_version >= '3.7'",
+            "version": "==23.2.0"
+        },
+        "black": {
+            "hashes": [
+                "sha256:0052dba51dec07ed029ed61b18183942043e00008ec65d5028814afaab9a22fd",
+                "sha256:0680d4380db3719ebcfb2613f34e86c8e6d15ffeabcf8ec59355c5e7b85bb555",
+                "sha256:121ca7f10b4a01fd99951234abdbd97728e1240be89fde18480ffac16503d481",
+                "sha256:162e37d49e93bd6eb6f1afc3e17a3d23a823042530c37c3c42eeeaf026f38468",
+                "sha256:2a951cc83ab535d248c89f300eccbd625e80ab880fbcfb5ac8afb5f01a258ac9",
+                "sha256:2bf649fda611c8550ca9d7592b69f0637218c2369b7744694c5e4902873b2f3a",
+                "sha256:382998821f58e5c8238d3166c492139573325287820963d2f7de4d518bd76958",
+                "sha256:49f7b39e30f326a34b5c9a4213213a6b221d7ae9d58ec70df1c4a307cf2a1580",
+                "sha256:57c18c5165c1dbe291d5306e53fb3988122890e57bd9b3dcb75f967f13411a26",
+                "sha256:7a0f701d314cfa0896b9001df70a530eb2472babb76086344e688829efd97d32",
+                "sha256:8178318cb74f98bc571eef19068f6ab5613b3e59d4f47771582f04e175570ed8",
+                "sha256:8b70eb40a78dfac24842458476135f9b99ab952dd3f2dab738c1881a9b38b753",
+                "sha256:9880d7d419bb7e709b37e28deb5e68a49227713b623c72b2b931028ea65f619b",
+                "sha256:9afd3f493666a0cd8f8df9a0200c6359ac53940cbde049dcb1a7eb6ee2dd7074",
+                "sha256:a29650759a6a0944e7cca036674655c2f0f63806ddecc45ed40b7b8aa314b651",
+                "sha256:a436e7881d33acaf2536c46a454bb964a50eff59b21b51c6ccf5a40601fbef24",
+                "sha256:a59db0a2094d2259c554676403fa2fac3473ccf1354c1c63eccf7ae65aac8ab6",
+                "sha256:a8471939da5e824b891b25751955be52ee7f8a30a916d570a5ba8e0f2eb2ecad",
+                "sha256:b0bd97bea8903f5a2ba7219257a44e3f1f9d00073d6cc1add68f0beec69692ac",
+                "sha256:b6a92a41ee34b883b359998f0c8e6eb8e99803aa8bf3123bf2b2e6fec505a221",
+                "sha256:bb460c8561c8c1bec7824ecbc3ce085eb50005883a6203dcfb0122e95797ee06",
+                "sha256:bfffba28dc52a58f04492181392ee380e95262af14ee01d4bc7bb1b1c6ca8d27",
+                "sha256:c1c476bc7b7d021321e7d93dc2cbd78ce103b84d5a4cf97ed535fbc0d6660648",
+                "sha256:c91dfc2c2a4e50df0026f88d2215e166616e0c80e86004d0003ece0488db2739",
+                "sha256:e6663f91b6feca5d06f2ccd49a10f254f9298cc1f7f49c46e498a0771b507104"
+            ],
+            "index": "pypi",
+            "version": "==23.1.0"
+        },
+        "click": {
+            "hashes": [
+                "sha256:ae74fb96c20a0277a1d615f1e4d73c8414f5a98db8b799a7931d1582f3390c28",
+                "sha256:ca9853ad459e787e2192211578cc907e7594e294c7ccc834310722b41b9ca6de"
+            ],
+            "markers": "python_version >= '3.7'",
+            "version": "==8.1.7"
+        },
+        "dill": {
+            "hashes": [
+                "sha256:76b122c08ef4ce2eedcd4d1abd8e641114bfc6c2867f49f3c41facf65bf19f5e",
+                "sha256:cc1c8b182eb3013e24bd475ff2e9295af86c1a38eb1aff128dac8962a9ce3c03"
+            ],
+            "markers": "python_version >= '3.11'",
+            "version": "==0.3.7"
+        },
+        "iniconfig": {
+            "hashes": [
+                "sha256:2d91e135bf72d31a410b17c16da610a82cb55f6b0477d1a902134b24a455b8b3",
+                "sha256:b6a85871a79d2e3b22d2d1b94ac2824226a63c6b741c88f7ae975f18b6778374"
+            ],
+            "markers": "python_version >= '3.7'",
+            "version": "==2.0.0"
+        },
+        "isort": {
+            "hashes": [
+                "sha256:48fdfcb9face5d58a4f6dde2e72a1fb8dcaf8ab26f95ab49fab84c2ddefb0109",
+                "sha256:8ca5e72a8d85860d5a3fa69b8745237f2939afe12dbf656afbcb47fe72d947a6"
+            ],
+            "markers": "python_full_version >= '3.8.0'",
+            "version": "==5.13.2"
+        },
+        "mccabe": {
+            "hashes": [
+                "sha256:348e0240c33b60bbdf4e523192ef919f28cb2c3d7d5c7794f74009290f236325",
+                "sha256:6c2d30ab6be0e4a46919781807b4f0d834ebdd6c6e3dca0bda5a15f863427b6e"
+            ],
+            "markers": "python_version >= '3.6'",
+            "version": "==0.7.0"
+        },
+        "mypy": {
+            "hashes": [
+                "sha256:19f905bcfd9e167159b3d63ecd8cb5e696151c3e59a1742e79bc3bcb540c42c7",
+                "sha256:21a1ad938fee7d2d96ca666c77b7c494c3c5bd88dff792220e1afbebb2925b5e",
+                "sha256:40b1844d2e8b232ed92e50a4bd11c48d2daa351f9deee6c194b83bf03e418b0c",
+                "sha256:41697773aa0bf53ff917aa077e2cde7aa50254f28750f9b88884acea38a16169",
+                "sha256:49ae115da099dcc0922a7a895c1eec82c1518109ea5c162ed50e3b3594c71208",
+                "sha256:4c46b51de523817a0045b150ed11b56f9fff55f12b9edd0f3ed35b15a2809de0",
+                "sha256:4cbe68ef919c28ea561165206a2dcb68591c50f3bcf777932323bc208d949cf1",
+                "sha256:4d01c00d09a0be62a4ca3f933e315455bde83f37f892ba4b08ce92f3cf44bcc1",
+                "sha256:59a0d7d24dfb26729e0a068639a6ce3500e31d6655df8557156c51c1cb874ce7",
+                "sha256:68351911e85145f582b5aa6cd9ad666c8958bcae897a1bfda8f4940472463c45",
+                "sha256:7274b0c57737bd3476d2229c6389b2ec9eefeb090bbaf77777e9d6b1b5a9d143",
+                "sha256:81af8adaa5e3099469e7623436881eff6b3b06db5ef75e6f5b6d4871263547e5",
+                "sha256:82e469518d3e9a321912955cc702d418773a2fd1e91c651280a1bda10622f02f",
+                "sha256:8b27958f8c76bed8edaa63da0739d76e4e9ad4ed325c814f9b3851425582a3cd",
+                "sha256:8c223fa57cb154c7eab5156856c231c3f5eace1e0bed9b32a24696b7ba3c3245",
+                "sha256:8f57e6b6927a49550da3d122f0cb983d400f843a8a82e65b3b380d3d7259468f",
+                "sha256:925cd6a3b7b55dfba252b7c4561892311c5358c6b5a601847015a1ad4eb7d332",
+                "sha256:a43ef1c8ddfdb9575691720b6352761f3f53d85f1b57d7745701041053deff30",
+                "sha256:a8032e00ce71c3ceb93eeba63963b864bf635a18f6c0c12da6c13c450eedb183",
+                "sha256:b96ae2c1279d1065413965c607712006205a9ac541895004a1e0d4f281f2ff9f",
+                "sha256:bb8ccb4724f7d8601938571bf3f24da0da791fe2db7be3d9e79849cb64e0ae85",
+                "sha256:bbaf4662e498c8c2e352da5f5bca5ab29d378895fa2d980630656178bd607c46",
+                "sha256:cfd13d47b29ed3bbaafaff7d8b21e90d827631afda134836962011acb5904b71",
+                "sha256:d4473c22cc296425bbbce7e9429588e76e05bc7342da359d6520b6427bf76660",
+                "sha256:d8fbb68711905f8912e5af474ca8b78d077447d8f3918997fecbf26943ff3cbb",
+                "sha256:e5012e5cc2ac628177eaac0e83d622b2dd499e28253d4107a08ecc59ede3fc2c",
+                "sha256:eb4f18589d196a4cbe5290b435d135dee96567e07c2b2d43b5c4621b6501531a"
+            ],
+            "index": "pypi",
+            "version": "==1.6.1"
+        },
+        "mypy-extensions": {
+            "hashes": [
+                "sha256:4392f6c0eb8a5668a69e23d168ffa70f0be9ccfd32b5cc2d26a34ae5b844552d",
+                "sha256:75dbf8955dc00442a438fc4d0666508a9a97b6bd41aa2f0ffe9d2f2725af0782"
+            ],
+            "markers": "python_version >= '3.5'",
+            "version": "==1.0.0"
+        },
+        "packaging": {
+            "hashes": [
+                "sha256:048fb0e9405036518eaaf48a55953c750c11e1a1b68e0dd1a9d62ed0c092cfc5",
+                "sha256:8c491190033a9af7e1d931d0b5dacc2ef47509b34dd0de67ed209b5203fc88c7"
+            ],
+            "markers": "python_version >= '3.7'",
+            "version": "==23.2"
+        },
+        "pathspec": {
+            "hashes": [
+                "sha256:a0d503e138a4c123b27490a4f7beda6a01c6f288df0e4a8b79c7eb0dc7b4cc08",
+                "sha256:a482d51503a1ab33b1c67a6c3813a26953dbdc71c31dacaef9a838c4e29f5712"
+            ],
+            "markers": "python_version >= '3.8'",
+            "version": "==0.12.1"
+        },
+        "platformdirs": {
+            "hashes": [
+                "sha256:11c8f37bcca40db96d8144522d925583bdb7a31f7b0e37e3ed4318400a8e2380",
+                "sha256:906d548203468492d432bcb294d4bc2fff751bf84971fbb2c10918cc206ee420"
+            ],
+            "markers": "python_version >= '3.8'",
+            "version": "==4.1.0"
+        },
+        "pluggy": {
+            "hashes": [
+                "sha256:cf61ae8f126ac6f7c451172cf30e3e43d3ca77615509771b3a984a0730651e12",
+                "sha256:d89c696a773f8bd377d18e5ecda92b7a3793cbe66c87060a6fb58c7b6e1061f7"
+            ],
+            "markers": "python_version >= '3.8'",
+            "version": "==1.3.0"
+        },
+        "pylint": {
+            "hashes": [
+                "sha256:0d4c286ef6d2f66c8bfb527a7f8a629009e42c99707dec821a03e1b51a4c1496",
+                "sha256:60ed5f3a9ff8b61839ff0348b3624ceeb9e6c2a92c514d81c9cc273da3b6bcda"
+            ],
+            "index": "pypi",
+            "version": "==3.0.2"
+        },
+        "pytest": {
+            "hashes": [
+                "sha256:c7c6ca206e93355074ae32f7403e8ea12163b1163c976fee7d4d84027c162be5",
+                "sha256:d45e0952f3727241918b8fd0f376f5ff6b301cc0777c6f9a556935c92d8a7d42"
+            ],
+            "index": "pypi",
+            "version": "==7.2.1"
+        },
+        "tomlkit": {
+            "hashes": [
+                "sha256:75baf5012d06501f07bee5bf8e801b9f343e7aac5a92581f20f80ce632e6b5a4",
+                "sha256:b0a645a9156dc7cb5d3a1f0d4bab66db287fcb8e0430bdd4664a095ea16414ba"
+            ],
+            "markers": "python_version >= '3.7'",
+            "version": "==0.12.3"
+        },
+        "types-requests": {
+            "hashes": [
+                "sha256:b32b9a86beffa876c0c3ac99a4cd3b8b51e973fb8e3bd4e0a6bb32c7efad80fc",
+                "sha256:dc5852a76f1eaf60eafa81a2e50aefa3d1f015c34cf0cba130930866b1b22a92"
+            ],
+            "index": "pypi",
+            "version": "==2.31.0.10"
+        },
+        "typing-extensions": {
+            "hashes": [
+                "sha256:23478f88c37f27d76ac8aee6c905017a143b0b1b886c3c9f66bc2fd94f9f5783",
+                "sha256:af72aea155e91adfc61c3ae9e0e342dbc0cba726d6cba4b6c72c1f34e47291cd"
+            ],
+            "markers": "python_version >= '3.8'",
+            "version": "==4.9.0"
+        },
+        "urllib3": {
+            "hashes": [
+                "sha256:55901e917a5896a349ff771be919f8bd99aff50b79fe58fec595eb37bbc56bb3",
+                "sha256:df7aa8afb0148fa78488e7899b2c59b5f4ffcfa82e6c54ccb9dd37c1d7b52d54"
+            ],
+            "markers": "python_version >= '3.8'",
+            "version": "==2.1.0"
+        }
+    }
+}
diff --git a/.github/scripts/python/validate-existing-contributors/__main__.py b/.github/scripts/python/validate-existing-contributors/__main__.py
new file mode 100644
index 00000000..6be85215
--- /dev/null
+++ b/.github/scripts/python/validate-existing-contributors/__main__.py
@@ -0,0 +1,90 @@
+"""
+© Ocado Group
+Created on 08/01/2024 at 09:47:25(+00:00).
+
+Validate all contributors have signed the contribution agreement.
+"""
+
+import json
+import os
+import typing as t
+from email.utils import parseaddr
+
+PullRequest = t.Dict[str, t.Any]
+Contributors = t.Set[str]
+
+# pylint: disable-next=line-too-long
+CONTRIBUTING_FILE_NAME = "CONTRIBUTING.md"
+CONTRIBUTORS_HEADER = "### 👨\u200d💻 Contributors 👩\u200d💻"
+
+
+def get_inputs():
+    """Get script's inputs.
+
+    Returns:
+        A JSON object of the pull request.
+    """
+
+    pull_request: PullRequest = json.loads(os.environ["PULL_REQUEST"])
+
+    return pull_request
+
+
+def get_signed_contributors() -> Contributors:
+    """Get the contributors that have signed the contribution agreement.
+
+    Returns:
+        A set of the contributors' email addresses.
+    """
+
+    with open(
+        f"../../../../{CONTRIBUTING_FILE_NAME}",
+        "r",
+        encoding="utf-8",
+    ) as contributing:
+        lines = contributing.read().splitlines()
+
+    # NOTE: +2 because we don't want the header and its proceeding blank line.
+    lines = lines[lines.index(CONTRIBUTORS_HEADER) + 2 :]
+
+    return {parseaddr(line)[1] for line in lines}
+
+
+def assert_contributors(
+    pull_request: PullRequest,
+    signed_contributors: Contributors,
+):
+    """Assert that all contributors have signed the contribution agreement.
+
+    Args:
+        pull_request: The JSON object of the pull request.
+        signed_contributors: The contributors that have signed the contribution
+            agreement.
+    """
+
+    contributors: Contributors = {
+        author["email"]
+        for commit in pull_request["commits"]
+        for author in commit["authors"]
+    }
+
+    unsigned_contributors = contributors.difference(signed_contributors)
+
+    assert not unsigned_contributors, (
+        "The following contributors have not signed the agreement:"
+        f" {', '.join(unsigned_contributors)}."
+    )
+
+
+def main():
+    """Entry point."""
+
+    pull_request = get_inputs()
+
+    signed_contributors = get_signed_contributors()
+
+    assert_contributors(pull_request, signed_contributors)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/.github/workflows/validate-existing-contributors.yaml b/.github/workflows/validate-existing-contributors.yaml
new file mode 100644
index 00000000..76e261ab
--- /dev/null
+++ b/.github/workflows/validate-existing-contributors.yaml
@@ -0,0 +1,41 @@
+name: Validate Existing Contributors
+
+on:
+  workflow_call:
+
+env:
+  PYTHON_VERSION: 3.11
+  WORKING_DIR: codeforlife-workspace/.github/scripts/python/validate-existing-contributors
+
+jobs:
+  validate-existing-contributors:
+    runs-on: ubuntu-latest
+    steps:
+      - name: 🛫 Checkout Pull Request
+        uses: actions/checkout@v4
+
+      - name: 🔎 View Pull Request's Commits
+        id: view-pr
+        run: echo "PULL_REQUEST=$(gh pr view ${{ github.event.pull_request.number }} --json commits)" >> $GITHUB_OUTPUT
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: 🛫 Checkout Workspace
+        uses: actions/checkout@v4
+        with:
+          repository: ocadotechnology/codeforlife-workspace
+          ref: main
+          path: codeforlife-workspace
+
+      - name: 🐍 Set up Python ${{ env.PYTHON_VERSION }} Environment
+        uses: ocadotechnology/codeforlife-workspace/.github/actions/python/setup-environment@main
+        with:
+          checkout: 'false'
+          python-version: ${{ env.PYTHON_VERSION }}
+          working-directory: ${{ env.WORKING_DIR }}
+
+      - name: 🕵️ Validate Existing Contributors
+        working-directory: ${{ env.WORKING_DIR }}
+        run: pipenv run python .
+        env:
+          PULL_REQUEST: ${{ steps.view-pr.outputs.PULL_REQUEST }}