diff --git a/lib/questionlib.php b/lib/questionlib.php
index e039ad9c534..201c6c68be1 100644
--- a/lib/questionlib.php
+++ b/lib/questionlib.php
@@ -389,10 +389,6 @@ function question_delete_question($questionid): void {
     // Delete questiontype-specific data.
     question_bank::get_qtype($question->qtype, false)->delete_question($question->id, $questiondata->contextid);
 
-    // Delete the custom filed data for the question.
-    $customfieldhandler = qbank_customfields\customfield\question_handler::create();
-    $customfieldhandler->delete_instance($question->id);
-
     // Now recursively delete all child questions
     if ($children = $DB->get_records('question',
             array('parent' => $questionid), '', 'id, qtype')) {
diff --git a/question/bank/customfields/classes/event/question_deleted_observer.php b/question/bank/customfields/classes/event/question_deleted_observer.php
new file mode 100644
index 00000000000..853c5a79119
--- /dev/null
+++ b/question/bank/customfields/classes/event/question_deleted_observer.php
@@ -0,0 +1,41 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace qbank_customfields\event;
+
+use core\event\question_deleted;
+use qbank_customfields\customfield\question_handler;
+
+/**
+ * Event observer for question deletion
+ *
+ * @package   qbank_customfields
+ * @copyright 2023 onwards Catalyst IT EU {@link https://catalyst-eu.net}
+ * @author    Mark Johnson <mark.johnson@catalyst-eu.net>
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class question_deleted_observer {
+
+    /**
+     * Delete any custom field data for the deleted question.
+     *
+     * @param question_deleted $event
+     * @return void
+     */
+    public static function delete_question_customfields(question_deleted $event): void {
+        question_handler::create()->delete_instance($event->objectid);
+    }
+}
diff --git a/question/bank/customfields/db/events.php b/question/bank/customfields/db/events.php
new file mode 100644
index 00000000000..311d7d34cab
--- /dev/null
+++ b/question/bank/customfields/db/events.php
@@ -0,0 +1,33 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Question custom fields events
+ *
+ * @package   qbank_customfields
+ * @copyright 2023 onwards Catalyst IT EU {@link https://catalyst-eu.net}
+ * @author    Mark Johnson <mark.johnson@catalyst-eu.net>
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+$observers = [
+    [
+        'eventname' => '\core\event\question_deleted',
+        'callback' => '\qbank_customfields\event\question_deleted_observer::delete_question_customfields'
+    ]
+];
diff --git a/question/bank/customfields/tests/event/question_deleted_observer_test.php b/question/bank/customfields/tests/event/question_deleted_observer_test.php
new file mode 100644
index 00000000000..bcbde6aa7b9
--- /dev/null
+++ b/question/bank/customfields/tests/event/question_deleted_observer_test.php
@@ -0,0 +1,68 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+namespace qbank_customfields\event;
+
+/**
+ * Tests for question_deleted_observer
+ *
+ * @package   qbank_customfields
+ * @copyright 2023 onwards Catalyst IT EU {@link https://catalyst-eu.net}
+ * @author    Mark Johnson <mark.johnson@catalyst-eu.net>
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ * @covers    \qbank_customfields\event\question_deleted_observer
+ */
+class question_deleted_observer_test extends \advanced_testcase {
+
+    /**
+     * Deleting a question with customfield data should also delete the data.
+     *
+     * @return void
+     */
+    public function test_delete_question_with_customfields(): void {
+        $this->resetAfterTest();
+        $generator = self::getDataGenerator();
+        $data = [
+            'component' => 'qbank_customfields',
+            'area' => 'question'
+        ];
+
+        $categoryid = $generator->create_custom_field_category($data)->get('id');
+        $generator->create_custom_field(['categoryid' => $categoryid, 'type' => 'text', 'shortname' => 'f1']);
+
+        $questiongenerator = $generator->get_plugin_generator('core_question');
+        [, , , $questions] = $questiongenerator->setup_course_and_questions();
+        $question = reset($questions);
+
+        $customfieldhandler = \qbank_customfields\customfield\question_handler::create();
+        $questiondata = (object)[
+            'id' => $question->id,
+            'customfield_f1' => random_string()
+        ];
+
+        $customfieldhandler->instance_form_save($questiondata);
+
+        $customdata = $customfieldhandler->get_instance_data($question->id);
+        $this->assertCount(1, $customdata);
+        $this->assertEquals($questiondata->customfield_f1, reset($customdata)->get_value());
+
+        question_delete_question($question->id);
+
+        $customdata = $customfieldhandler->get_instance_data($question->id);
+        $this->assertCount(1, $customdata);
+        $this->assertEmpty(reset($customdata)->get_value());
+    }
+}
diff --git a/question/bank/customfields/version.php b/question/bank/customfields/version.php
index 4ee627e03d1..077a36e5d51 100644
--- a/question/bank/customfields/version.php
+++ b/question/bank/customfields/version.php
@@ -26,6 +26,6 @@
 defined('MOODLE_INTERNAL') || die();
 
 $plugin->component = 'qbank_customfields';
-$plugin->version   = 2023042400;
+$plugin->version   = 2023042401;
 $plugin->requires  = 2023041800;
 $plugin->maturity  = MATURITY_STABLE;