For advanced searching to show only the discounted fare classes, you can search with "secret" commands. There are a bunch of different inventor codes (e.g., the "A" booking class is the discounted first class). See Hack My Trip for the advanced search codes.
'Navy Week', SR poster, 1930., Carr, Leslie Poster produced for the Southern Railway (SR) to promote cheap day tickets to the dockyards of Chatham, Portsmouth and Devonport open to the public during Navy Week. The poster shows an illustration of a vesel being repaired.jul16