When I go to the premium dashboard it flashes the correct currency (USD in my case) for a split second and then jumps to GBP.
It changes the currency to the one used in whichever country you're connecting from; if you're not using a proxy/VPN then it's probably just an error in the geolocation database.
After you select the country and click continue, it will change it to the respective currency.
Bah, totally forgot I had my VPN running. Silly. Must need more coffee.