diff --git a/app/Services/PostcodeService.php b/app/Services/PostcodeService.php
index 7c27a2b..9489e98 100644
--- a/app/Services/PostcodeService.php
+++ b/app/Services/PostcodeService.php
@@ -47,6 +47,11 @@ class PostcodeService
         return $result;
     }
 
+    private function normalisePostcode(string $value): string
+    {
+        return strtoupper(preg_replace('/\s+/', '', $value));
+    }
+
     private function isFullPostcode(string $query): bool
     {
         return (bool) preg_match('/^[A-Z]{1,2}[0-9][0-9A-Z]?\s*[0-9][A-Z]{2}$/i', $query);
@@ -59,7 +64,7 @@ class PostcodeService
 
     private function lookupLocalPostcode(string $postcode): ?LocationResult
     {
-        $normalised = strtoupper(preg_replace('/\s+/', '', $postcode));
+        $normalised = $this->normalisePostcode($postcode);
 
         $row = Postcode::find($normalised);
 
@@ -105,7 +110,7 @@ class PostcodeService
 
     private function lookupPostcode(string $postcode): ?LocationResult
     {
-        $normalised = strtoupper(preg_replace('/\s+/', '', $postcode));
+        $normalised = $this->normalisePostcode($postcode);
         $url = self::BASE_URL.'/postcodes/'.$normalised;
 
         try {
@@ -117,12 +122,23 @@ class PostcodeService
 
             $data = $response->json('result');
 
-            return new LocationResult(
+            $result = new LocationResult(
                 query: $postcode,
                 displayName: $data['postcode'],
                 lat: $data['latitude'],
                 lng: $data['longitude'],
             );
+
+            Postcode::updateOrCreate(
+                ['postcode' => $normalised],
+                [
+                    'outcode' => substr($normalised, 0, strlen($normalised) - 3),
+                    'lat' => $data['latitude'],
+                    'lng' => $data['longitude'],
+                ],
+            );
+
+            return $result;
         } catch (Throwable $e) {
             Log::error('PostcodeService: postcode lookup failed', [
                 'postcode' => $postcode,
@@ -147,12 +163,22 @@ class PostcodeService
 
             $data = $response->json('result');
 
-            return new LocationResult(
+            $result = new LocationResult(
                 query: $outcode,
                 displayName: $data['outcode'],
                 lat: $data['latitude'],
                 lng: $data['longitude'],
             );
+
+            Outcode::updateOrCreate(
+                ['outcode' => $normalised],
+                [
+                    'lat' => $data['latitude'],
+                    'lng' => $data['longitude'],
+                ],
+            );
+
+            return $result;
         } catch (Throwable $e) {
             Log::error('PostcodeService: outcode lookup failed', [
                 'outcode' => $outcode,
diff --git a/tests/Unit/Services/PostcodeServiceTest.php b/tests/Unit/Services/PostcodeServiceTest.php
index 464ef8e..f3bc4ea 100644
--- a/tests/Unit/Services/PostcodeServiceTest.php
+++ b/tests/Unit/Services/PostcodeServiceTest.php
@@ -216,3 +216,48 @@ it('resolves an outcode from local DB without calling HTTP', function (): void {
 
     Http::assertNothingSent();
 });
+
+// --- HTTP fallback persistence ---
+
+it('persists a full postcode resolved via HTTP fallback', function (): void {
+    Http::fake([
+        '*/postcodes/SW1A1AA' => Http::response([
+            'status' => 200,
+            'result' => [
+                'postcode' => 'SW1A 1AA',
+                'latitude' => 51.501009,
+                'longitude' => -0.141588,
+            ],
+        ]),
+    ]);
+
+    $this->service->resolve('SW1A 1AA');
+
+    $row = Postcode::find('SW1A1AA');
+
+    expect($row)->not->toBeNull()
+        ->and($row->outcode)->toBe('SW1A')
+        ->and((float) $row->lat)->toBe(51.501009)
+        ->and((float) $row->lng)->toBe(-0.141588);
+});
+
+it('persists an outcode resolved via HTTP fallback', function (): void {
+    Http::fake([
+        '*/outcodes/PE7' => Http::response([
+            'status' => 200,
+            'result' => [
+                'outcode' => 'PE7',
+                'latitude' => 52.536397,
+                'longitude' => -0.210181,
+            ],
+        ]),
+    ]);
+
+    $this->service->resolve('PE7');
+
+    $row = Outcode::find('PE7');
+
+    expect($row)->not->toBeNull()
+        ->and((float) $row->lat)->toBe(52.536397)
+        ->and((float) $row->lng)->toBe(-0.210181);
+});