At the price paid for RT Business Class these days, I wouldn't think an extra 55 quid would make a difference!
You wouldn't think they would do it then? They don't charge extra in First class and that is usually (not always) even pricier. By the way, the £55 isn't for
RT Business class, it is for
one way business class. If you want to select your seats for "RT" then it is at least £110 each! Although I think
backtrack's party were only booking "C" one way, for a family of four booking R/T, another £440 is quite a bite.