Originally Posted by
visualAd
In my experience you actually have to ask for business UK when you buy the domestic ticket at the airport; otherwise its just booked in one of the expensive fare buckets, not flexible and no lounge access (boarding card should say 'J' if its business UK, Y and the other expensive ones won't give you the lounge access).
Domestic Full fare Y gives you lounge access as it's a fully flexible fare, I've been booked in that class many times and the iPhone app always reflects Business UK as it does with J class