I'm in standard premium right now, the only one in the coach. £25 upgrade which must be too steep, and no discount for Railcard, however when booking you do get that discount...but only on Avanti site and not if you have a longer journey on the ticket, eg Manchester to London the tickets available, Manchester to Brighton it isn't.
I booked 2 separate tickets, so I could have SP + Railcard discount on this leg for SP.
Think the selling of the ticket needs looking at as it's unavailable on other booking engines too I think?