diff --git a/manage_breast_screening/assets/sass/main.scss b/manage_breast_screening/assets/sass/main.scss
index 653cc8313..9ba3af6f7 100644
--- a/manage_breast_screening/assets/sass/main.scss
+++ b/manage_breast_screening/assets/sass/main.scss
@@ -51,6 +51,24 @@ a[href="#"] {
   color: #c80000 !important;
 }
 
+// Environment banner at the top of the page
+.app-environment {
+  @include nhsuk-font-size(14);
+  @include nhsuk-responsive-padding(2, bottom);
+  @include nhsuk-responsive-padding(2, top);
+
+  .nhsuk-link {
+    color: inherit;
+  }
+
+  .nhsuk-width-container {
+    align-items: baseline;
+    display: flex;
+    flex-wrap: wrap;
+    gap: nhsuk-spacing(1) nhsuk-spacing(2);
+  }
+}
+
 // Status tag positioning within headers
 .app-header {
   position: relative;
diff --git a/manage_breast_screening/config/jinja2_env.py b/manage_breast_screening/config/jinja2_env.py
index 3c1628956..857b59fe6 100644
--- a/manage_breast_screening/config/jinja2_env.py
+++ b/manage_breast_screening/config/jinja2_env.py
@@ -41,6 +41,7 @@ def environment(**options):
             "raise": raise_helper,
             "static": static,
             "url": reverse,
+            "DJANGO_ENV": settings.DJANGO_ENV,
         }
     )
 
diff --git a/manage_breast_screening/config/settings/base.py b/manage_breast_screening/config/settings/base.py
index 3cf04ebc3..c0dfe6b81 100644
--- a/manage_breast_screening/config/settings/base.py
+++ b/manage_breast_screening/config/settings/base.py
@@ -34,6 +34,8 @@ def list_env(key):
 
 DJANGO_ENV = environ.get("DJANGO_ENV", "production")
 
+IS_PRODUCTION = DJANGO_ENV == "production"
+
 ALLOWED_HOSTS = list_env("ALLOWED_HOSTS")
 CSRF_TRUSTED_ORIGINS = list_env("CSRF_TRUSTED_ORIGINS")
 
@@ -76,7 +78,7 @@ def list_env(key):
     "ninja",
 ]
 
-if DJANGO_ENV != "production":
+if not IS_PRODUCTION:
     INSTALLED_APPS.append("manage_breast_screening.nonprod")
 
 MIDDLEWARE = [
@@ -178,7 +180,7 @@ def list_env(key):
 }
 
 
-if DJANGO_ENV != "production":
+if not IS_PRODUCTION:
     if environ.get("BLOB_STORAGE_CONNECTION_STRING"):
         # Use connection string if provided (e.g., in local development using Azurite)
         dicom_storage_options = {
diff --git a/manage_breast_screening/core/jinja2/layout-app.jinja b/manage_breast_screening/core/jinja2/layout-app.jinja
index c1ca3ab5b..0f05191ea 100644
--- a/manage_breast_screening/core/jinja2/layout-app.jinja
+++ b/manage_breast_screening/core/jinja2/layout-app.jinja
@@ -14,6 +14,17 @@
 {% block pageTitle %}{% if form and form.errors %}Error: {% endif %}{% if page_title %}{{ page_title }} – {% endif %}Manage breast screening – NHS{% endblock %}
 
 {% block header %}
+  {% if not IS_PRODUCTION %}
+    <div class="app-environment nhsuk-tag--grey">
+      <div class="nhsuk-width-container">
+        <strong class="nhsuk-tag nhsuk-tag--grey">
+          {{ DJANGO_ENV }}
+        </strong>
+        This is the {{ DJANGO_ENV }} environment.
+      </div>
+    </div>
+  {% endif %}
+
   {{ header({
     "classes": "nhsuk-header--inline",
     "service": {
diff --git a/manage_breast_screening/nonprod/management/commands/seed_demo_data.py b/manage_breast_screening/nonprod/management/commands/seed_demo_data.py
index fe5166dbb..24977a3f4 100644
--- a/manage_breast_screening/nonprod/management/commands/seed_demo_data.py
+++ b/manage_breast_screening/nonprod/management/commands/seed_demo_data.py
@@ -1,6 +1,5 @@
 import logging
 from datetime import datetime, timedelta
-from os import getenv
 
 import yaml
 from django.conf import settings
@@ -79,7 +78,7 @@ def diagram_file(self, file_name):
         return open(MAMMOGRAM_DIAGRAMS_DIR / file_name, "rb")
 
     def handle(self, *args, **kwargs):
-        if getenv("DJANGO_ENV", "production") == "production":
+        if settings.IS_PRODUCTION:
             raise Exception("This command cannot be run in production")
 
         if not kwargs["noinput"]: