diff --git a/schemas/app.json b/schemas/app.json
index e436a7ef..adbb73cd 100644
--- a/schemas/app.json
+++ b/schemas/app.json
@@ -26,96 +26,6 @@
       ],
       "type": "object"
     },
-    "BaseWTT": {
-      "additionalProperties": false,
-      "properties": {
-        "applicationType": {
-          "const": "wtt",
-          "type": "string"
-        },
-        "data": {
-          "additionalProperties": false,
-          "properties": {
-            "application": {
-              "$ref": "#/definitions/WTTApplicationData"
-            },
-            "user": {
-              "$ref": "#/definitions/WTTUser"
-            }
-          },
-          "required": [
-            "user",
-            "application"
-          ],
-          "type": "object"
-        }
-      },
-      "required": [
-        "applicationType",
-        "data"
-      ],
-      "type": "object"
-    },
-    "ConsentWTT": {
-      "additionalProperties": false,
-      "properties": {
-        "applicationType": {
-          "const": "wtt.consent",
-          "type": "string"
-        },
-        "data": {
-          "additionalProperties": false,
-          "properties": {
-            "application": {
-              "$ref": "#/definitions/WTTApplicationData"
-            },
-            "user": {
-              "$ref": "#/definitions/WTTUser"
-            }
-          },
-          "required": [
-            "user",
-            "application"
-          ],
-          "type": "object"
-        }
-      },
-      "required": [
-        "applicationType",
-        "data"
-      ],
-      "type": "object"
-    },
-    "NoticeWTT": {
-      "additionalProperties": false,
-      "properties": {
-        "applicationType": {
-          "const": "wtt.notice",
-          "type": "string"
-        },
-        "data": {
-          "additionalProperties": false,
-          "properties": {
-            "application": {
-              "$ref": "#/definitions/WTTApplicationData"
-            },
-            "user": {
-              "$ref": "#/definitions/WTTUser"
-            }
-          },
-          "required": [
-            "user",
-            "application"
-          ],
-          "type": "object"
-        }
-      },
-      "required": [
-        "applicationType",
-        "data"
-      ],
-      "type": "object"
-    },
     "PPApplicationData": {
       "additionalProperties": false,
       "description": "Specific ApplicationData required for \"Planning Permission\" applications",
@@ -270,17 +180,38 @@
       "type": "object"
     },
     "WorksToTreesApplications": {
-      "anyOf": [
-        {
-          "$ref": "#/definitions/BaseWTT"
-        },
-        {
-          "$ref": "#/definitions/ConsentWTT"
+      "additionalProperties": false,
+      "properties": {
+        "applicationType": {
+          "enum": [
+            "wtt",
+            "wtt.consent",
+            "wtt.notice"
+          ],
+          "type": "string"
         },
-        {
-          "$ref": "#/definitions/NoticeWTT"
+        "data": {
+          "additionalProperties": false,
+          "properties": {
+            "application": {
+              "$ref": "#/definitions/WTTApplicationData"
+            },
+            "user": {
+              "$ref": "#/definitions/WTTUser"
+            }
+          },
+          "required": [
+            "user",
+            "application"
+          ],
+          "type": "object"
         }
-      ]
+      },
+      "required": [
+        "applicationType",
+        "data"
+      ],
+      "type": "object"
     }
   },
   "description": "(Temporary name to not clash with the existing `Application` type)\nThe root specification for a planning application in England generated by a digital planning service",
diff --git a/types/schemas/app/index.ts b/types/schemas/app/index.ts
index 8cd96be2..e520863a 100644
--- a/types/schemas/app/index.ts
+++ b/types/schemas/app/index.ts
@@ -31,10 +31,10 @@ export type PlanningPermissionApplication = ApplicationSpecification<
 export type PriorApprovalApplication = ApplicationSpecification<'pa', 'pa'>;
 // TODO: All granular types
 
-export type WorksToTreesApplications = BaseWTT | ConsentWTT | NoticeWTT;
-export type BaseWTT = ApplicationSpecification<'wtt', 'wtt'>;
-export type ConsentWTT = ApplicationSpecification<'wtt', 'wtt.consent'>;
-export type NoticeWTT = ApplicationSpecification<'wtt', 'wtt.notice'>;
+export type WorksToTreesApplications = ApplicationSpecification<
+  'wtt',
+  Extract<ApplicationTypeKeys, 'wtt' | 'wtt.consent' | 'wtt.notice'>
+>;
 
 /**
  * @title App