diff --git a/data_safe_haven/functions/__init__.py b/data_safe_haven/functions/__init__.py
index 5d9ce25cce..1e8ab4edfc 100644
--- a/data_safe_haven/functions/__init__.py
+++ b/data_safe_haven/functions/__init__.py
@@ -7,7 +7,6 @@
     alphanumeric,
     b64encode,
     password,
-    random_letters,
     replace_separators,
     sanitise_sre_name,
     seeded_uuid,
@@ -21,7 +20,6 @@
     "b64encode",
     "ordered_private_dns_zones",
     "password",
-    "random_letters",
     "replace_separators",
     "sanitise_sre_name",
     "seeded_uuid",
diff --git a/data_safe_haven/functions/strings.py b/data_safe_haven/functions/strings.py
index ad68e379a0..31f099e4e0 100644
--- a/data_safe_haven/functions/strings.py
+++ b/data_safe_haven/functions/strings.py
@@ -38,11 +38,6 @@ def password(length: int) -> str:
     return password_
 
 
-def random_letters(length: int) -> str:
-    """Generate a string of 'length' random letters."""
-    return "".join(secrets.choice(string.ascii_letters) for _ in range(length))
-
-
 def replace_separators(input_string: str, separator: str = "") -> str:
     """Return a string using underscores as a separator"""
     return (