Change order of currencies in header

I want to change the order that the currencies are displayed in in the page header - at the moment they are displayed as €-£-$ and I want them to display as £-€-$

I've tried to change them by removing the second one down (Pound Sterling) in System | Localisation | Currencies, then putting it back in, in the hope that it would appear at the top. It didn't so I assume the list is alphabetical.

Does anyone know a way of changing the order of them in the header?