Just came across this. http://www.southwesttrains.co.uk/advance-fares.aspx It says in the 'How to Buy' section: I thought that the booking engine closes at 1800 or thereabouts the day before travel. Some TOCs might be as late as 2000 but never have I heard of the deadline being so late. Has anything changed lately? Also this The National Rail website states that So is it a case of the two listed being excluded as they're not truly 'national'?