GUI Text Doesn't Show '£' Symbol

Hello,

When I use the British Pound Sterling symbol (£) in GUI Text, it displays a question mark. I'm guessing this is because the £ symbol isn't included in the font package? How would I go about adding it?

The weird thing is, I am using an Arial font, which I know for a fact has a '£' included in the font package. So what could be causing it?

Thanks