diff --git a/agenda/holidays.py b/agenda/holidays.py
index 175e798..b0af818 100644
--- a/agenda/holidays.py
+++ b/agenda/holidays.py
@@ -17,7 +17,7 @@ def get_trip_holidays(trip: Trip) -> list[Holiday]:
     """Get holidays happening during trip."""
     if not trip.end:
         return []
-    countries = {c.alpha_2 for c in trip.countries}
+    countries = {"GB", *(c.alpha_2 for c in trip.countries)}
     return sorted(
         (
             hol
diff --git a/tests/test_holidays.py b/tests/test_holidays.py
new file mode 100644
index 0000000..ac428b2
--- /dev/null
+++ b/tests/test_holidays.py
@@ -0,0 +1,42 @@
+"""Tests for holiday selection."""
+
+from datetime import date
+from unittest import mock
+
+import flask
+
+import agenda.holidays
+from agenda.types import Holiday, Trip
+
+
+def test_trip_holidays_include_uk_bank_holiday_for_international_trip() -> None:
+    """UK bank holidays remain relevant while travelling internationally."""
+    trip = Trip(
+        start=date(2026, 8, 23),
+        accommodation=[
+            {
+                "name": "Paris hotel",
+                "location": "Paris",
+                "country": "fr",
+                "from": date(2026, 8, 23),
+                "to": date(2026, 8, 31),
+            }
+        ],
+    )
+    summer_bank_holiday = Holiday(
+        date=date(2026, 8, 31),
+        name="Summer bank holiday",
+        country="gb",
+    )
+    app = flask.Flask(__name__)
+    app.config["DATA_DIR"] = "/unused"
+
+    with (
+        app.app_context(),
+        mock.patch.object(
+            agenda.holidays,
+            "get_all",
+            return_value=[summer_bank_holiday],
+        ),
+    ):
+        assert agenda.holidays.get_trip_holidays(trip) == [summer_bank_holiday]