diff --git a/app/celery/tasks.py b/app/celery/tasks.py
index ae16f6c5e..4488f551d 100644
--- a/app/celery/tasks.py
+++ b/app/celery/tasks.py
@@ -1,3 +1,5 @@
+import random
+
 import botocore
 from boto3 import resource
 from datetime import (datetime)
@@ -266,7 +268,9 @@ def build_dvla_file(self, job_id):
         file = ""
         for n in notifications:
             t = {"content": n.template.content, "subject": n.template.subject}
-            template = LetterDVLATemplate(t, n.personalisation, 1)
+            # This unique id is a 7 digits requested by DVLA, not known if this number needs to be sequential.
+            unique_id = int(''.join(map(str, random.sample(range(9), 7))))
+            template = LetterDVLATemplate(t, n.personalisation, unique_id)
             # print(str(template))
             file = file + str(template) + "\n"
         s3upload(filedata=file,