I've been looking at returns from Cambridge (CBG) to King's Cross (KGX). One part of the Great Northern website (see screenshot1) says that Super Off-peak returns are available only to London Bridge, Blackfriars, City Thameslink, Farringdon and St Pancras (ie not King's Cross). Yet another part of the website (see screenshot2) is happy to sell me a Super Off-Peak return on the 1002 from CBG, which runs directly to King's Cross and terminates there. What am I missing, to understand which is correct please?