I looked at the ticket chart today and noticed some odd pricing for single tickets.
Basic Fare is £21 is you buy before you board.
There is a £5 penalty if you forget to get a ticket in advance and buy on board.
The Business First Class Fare – however you buy it (on board or in advance) is only £3 more than the on-board Express (2nd Class) ticket price.
Return fares clearly represent much better value.
However the Carnet – even if you buy it on board – is (relatively) amazing value for 12 trips. £15.75 in Express Class or £21.75 in Business First.
So, if you plan to take six roundtrips in a year, look at the Carnet for a discount of 25%.