As Mark points out, getting two tickets together (even non-bargain berths) is a nightmare … I was able to book two singles for £66 each for a Sunday evening back to London from Arbroath. Had I booked them as a pair, it would have been nearly £300! We ended up in adjoining compartments, but luckily one had a spare berth, so the hostess let us swap (she’d guessed we’d want to – as they were both booked in the same name)
(Though I did manage to get a £29 on recently to Arbroath -as Mark found – mid-week [in February])