Special characters: Where are "favorites" stored?

I love using the Special Characters, and have built up quite a few favourites that I use regularly. I have an iMac and a Macbook, and for some reason, all of a sudden, all of my favourite characters have disappeared from the Macbook's Character Viewer. It's now blank.

They are still present on the iMac, so I can just copy them across, but I don't know where the (?.plist) file that specifies my favourites actually lives...

Can anyone help?

Thanks

Giles