Example. Diss to Birmingham New Street via London and Glasgow Central to Diss via London. Can't remember which way round I ended up doing it, but one ticket I got from GA, and the other from Raileasy. I think the former one I could only get an advance from GA. Which sort of might make sense but really doesn't. The latter GA's site flat out said "there are no tickets available for this journey" or words to that effect. Whereas Raileasy displayed a range of options, including advances. Why would 2 sites show different availablity if they are working with the same source data?