diff --git a/projects/cas3-and-delius/src/integrationTest/kotlin/uk/gov/justice/digital/hmpps/CASIntegrationTest.kt b/projects/cas3-and-delius/src/integrationTest/kotlin/uk/gov/justice/digital/hmpps/CASIntegrationTest.kt
index 03bc58fe1a..d8dcaa5196 100644
--- a/projects/cas3-and-delius/src/integrationTest/kotlin/uk/gov/justice/digital/hmpps/CASIntegrationTest.kt
+++ b/projects/cas3-and-delius/src/integrationTest/kotlin/uk/gov/justice/digital/hmpps/CASIntegrationTest.kt
@@ -48,7 +48,7 @@ internal class CASIntegrationTest {
         Mockito.verify(telemetryService).notificationReceived(event)
 
         val contact =
-            contactRepository.getByExternalReference(event.message.additionalInformation["applicationId"] as String)
+            contactRepository.getByExternalReference("urn:hmpps:cas3:application-submitted:${event.message.additionalInformation["applicationId"] as String}")
 
         MatcherAssert.assertThat(contact!!.type.code, Matchers.equalTo("EARS"))
     }
@@ -64,7 +64,7 @@ internal class CASIntegrationTest {
         Mockito.verify(telemetryService).notificationReceived(event)
 
         val contact =
-            contactRepository.getByExternalReference("14c80733-4b6d-4f35-b724-66955aac320c")
+            contactRepository.getByExternalReference("urn:hmpps:cas3:booking-cancelled:14c80733-4b6d-4f35-b724-66955aac320c")
 
         MatcherAssert.assertThat(contact!!.type.code, Matchers.equalTo("EACA"))
     }
@@ -80,7 +80,7 @@ internal class CASIntegrationTest {
         Mockito.verify(telemetryService).notificationReceived(event)
 
         val contact =
-            contactRepository.getByExternalReference("14c80733-4b6d-4f35-b724-66955aac320d")
+            contactRepository.getByExternalReference("urn:hmpps:cas3:booking-confirmed:14c80733-4b6d-4f35-b724-66955aac320d")
 
         MatcherAssert.assertThat(contact!!.type.code, Matchers.equalTo("EACO"))
     }
@@ -96,7 +96,7 @@ internal class CASIntegrationTest {
         Mockito.verify(telemetryService).notificationReceived(event)
 
         val contact =
-            contactRepository.getByExternalReference("14c80733-4b6d-4f35-b724-66955aac320e")
+            contactRepository.getByExternalReference("urn:hmpps:cas3:booking-provisionally-made:14c80733-4b6d-4f35-b724-66955aac320e")
 
         MatcherAssert.assertThat(contact!!.type.code, Matchers.equalTo("EABP"))
     }
diff --git a/projects/cas3-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/integrations/approvedpremesis/Cas3ApiClient.kt b/projects/cas3-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/integrations/approvedpremesis/Cas3ApiClient.kt
index 756df7281a..61e83c6a5f 100644
--- a/projects/cas3-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/integrations/approvedpremesis/Cas3ApiClient.kt
+++ b/projects/cas3-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/integrations/approvedpremesis/Cas3ApiClient.kt
@@ -18,8 +18,8 @@ interface Cas3ApiClient {
     fun getBookingCancelledDetails(uri: URI): EventDetails<BookingCancelled>
 
     @GetMapping
-    fun getBookingConfirmedDetails(uri: URI): EventDetails<BookingProvisionalOrConfirmed>
+    fun getBookingConfirmedDetails(uri: URI): EventDetails<BookingConfirmed>
 
     @GetMapping
-    fun getBookingProvisionallyMade(uri: URI): EventDetails<BookingProvisionalOrConfirmed>
+    fun getBookingProvisionallyMade(uri: URI): EventDetails<BookingProvisional>
 }
diff --git a/projects/cas3-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/integrations/approvedpremesis/EventDetails.kt b/projects/cas3-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/integrations/approvedpremesis/EventDetails.kt
index 838406fafb..69bf6e2c2a 100644
--- a/projects/cas3-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/integrations/approvedpremesis/EventDetails.kt
+++ b/projects/cas3-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/integrations/approvedpremesis/EventDetails.kt
@@ -11,7 +11,9 @@ data class EventDetails<T>(
 
 data class ApplicationSubmitted(
     val applicationId: String
-)
+) {
+    val urn = "urn:hmpps:cas3:application-submitted:$applicationId"
+}
 
 data class BookingCancelled(
     val applicationId: String?,
@@ -20,13 +22,28 @@ data class BookingCancelled(
     val bookingUrl: String,
     val cancellationReason: String,
     val cancellationContext: String?
-)
+) {
+    val urn = "urn:hmpps:cas3:booking-cancelled:$bookingId"
+}
 
-data class BookingProvisionalOrConfirmed(
+data class BookingProvisional(
     val applicationId: String?,
     val applicationUrl: String?,
     val bookingId: String,
     val bookingUrl: String,
     val expectedArrivedAt: ZonedDateTime,
     val notes: String
-)
+) {
+    val urn = "urn:hmpps:cas3:booking-provisionally-made:$bookingId"
+}
+
+data class BookingConfirmed(
+    val applicationId: String?,
+    val applicationUrl: String?,
+    val bookingId: String,
+    val bookingUrl: String,
+    val expectedArrivedAt: ZonedDateTime,
+    val notes: String
+) {
+    val urn = "urn:hmpps:cas3:booking-confirmed:$bookingId"
+}
diff --git a/projects/cas3-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/integrations/delius/ContactService.kt b/projects/cas3-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/integrations/delius/ContactService.kt
index f4a5d2e893..aa299f11cc 100644
--- a/projects/cas3-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/integrations/delius/ContactService.kt
+++ b/projects/cas3-and-delius/src/main/kotlin/uk/gov/justice/digital/hmpps/integrations/delius/ContactService.kt
@@ -36,7 +36,7 @@ class ContactService(
     fun createReferralSubmitted(event: HmppsDomainEvent) {
         val details = cas3ApiClient.getApplicationSubmittedDetails(event.url()).eventDetails
         val crn = event.crn()
-        val externalReference = details.applicationId
+        val externalReference = details.urn
 
         if (contactRepository.getByExternalReference(externalReference) != null) {
             telemetryService.trackEvent("Duplicate ApplicationSubmitted event received for crn $crn")
@@ -54,39 +54,36 @@ class ContactService(
     fun createBookingCancelled(event: HmppsDomainEvent) {
         val details = cas3ApiClient.getBookingCancelledDetails(event.url()).eventDetails
         val crn = event.crn()
-        val externalReference = details.bookingId
         createContact(
             event.occurredAt,
             crn,
             "${details.cancellationReason} ${details.cancellationContext} ${details.bookingUrl}",
             BOOKING_CANCELLED,
-            externalReference
+            details.urn
         )
     }
 
     fun createBookingConfirmed(event: HmppsDomainEvent) {
         val details = cas3ApiClient.getBookingConfirmedDetails(event.url()).eventDetails
         val crn = event.crn()
-        val externalReference = details.bookingId
         createContact(
             event.occurredAt,
             crn,
             "${details.expectedArrivedAt} ${details.notes} ${details.bookingUrl}",
             BOOKING_CONFIRMED,
-            externalReference
+            details.urn
         )
     }
 
     fun createBookingProvisionallyMade(event: HmppsDomainEvent) {
         val crn = event.crn()
         val details = cas3ApiClient.getBookingProvisionallyMade(event.url()).eventDetails
-        val externalReference = details.bookingId
         createContact(
             event.occurredAt,
             crn,
             "${details.expectedArrivedAt} ${details.notes} ${details.bookingUrl}",
             BOOKING_PROVISIONAL,
-            externalReference
+            details.urn
         )
     }