Missing "Toggle Editor" Button - Joomla

I have super administrator rights to a Joomla site but the "Toggle Editor" button is missing Any idea how 开发者_如何学运维to get it back?

Many thanks, Steph

---

Do you mean this is missing? alt text http://www.toughtomato.com/websites/test/images/screenshots/screenshot1.png

If not then please could you be specific as to where this "Toggle Editor" button is meant to exist.