Scratching my head on this one. I like to get the 1945 Doncaster to Stevenage on Sundays - it reduces my overall journey time by 1 hour. Some Sundays it runs, others not. Yesterday it was not listed on the live departure boards but was listed clearly on the printed timetable near the platform - it never came. Next Sunday (13th) it runs, the Sunday after (20th) it has disappeared again. Any ideas why?