Thanks. Restoring that fixed it – however Sucuri did not pick up the change, nor a malicious login.
Fatal error: Namespace declaration statement has to be the very first statement or after any declare call in the script in XXX/wp-content/plugins/photonic/Core/Photonic.php on line 2
OK, so it seems that running a single repair table in phpmyadmin (I only repaired wp_usermeta) has fixed it. Weird.
Resolved. I hadn’t looked there – thank you. All in one calendar was the culprit. Have disabled it for now and will re-enable once fixed.
I am not with godaddy so that can’t be it.