Solved! For some reason I had changed the name of my custom post type slightly, in my register_custom_post_types.php file
register_post_type('programmes', array(
I changed the name back and they reappeared…
I’ve learnt to keep in mind how changes to things can affect WP’s ability to retrieve data
Edit: On further investigation it appears that the custom post type names became invalid because they were changed after the ‘init’ action, so stopping the virtual machine and restarting actually would have resolved the problem too