Disable directory indexes

.htaccess

 CheckSpelling Off
+Options -Indexes
 
 RewriteEngine on
 
@@ -15,4 +16,5 @@ RewriteRule ^ca($|/) http://psvg.doc.ic.ac.uk/research/concurrency.html [R=301,L
 RewriteCond %{HTTP_HOST} !=psvg.doc.ic.ac.uk
 RewriteRule ^(.*)$ http://psvg.doc.ic.ac.uk/$1 [R=301,L]
 
+ErrorDocument 403 /403.html
 ErrorDocument 404 /404.html

403.md

+---
+layout: page
+title: "Error 403: Page Not Found"
+permalink: /403.html
+---
+
+Oops :(. This page is not verified, therefore clients should not access it.