CakePHP, .htaccess and clean homepage urls

Sometimes we need a clean url for the homepage to appear in the browser address bar, e.g. www.example.com

This problem came up with the CMS system I have built as all the pages have a url/name. For example, the default homepage would show as www.example.com/homepage.

Typing www.example.com would redirect to this and change the displayed url. The desired behaviour is to redirect

www.example.com -> www.example.com/homepage but only display www.example.com.

On the other hand, if you were to type www.example.com/homepage the display should stay as www.example.com/homepage .

The answer means a slight change to the default CakePHP .htaccess file

RewriteRule ^$ app/webroot/ [L]

becomes
RewriteRule ^$ homepage [L]

Of course, homepage could be any page name that you want to be the anchor page.