Just one comment when using it to query BA flights. BA has 4 travel classes, Economy, Premium Economy, Business and First. When the results are shown, it goes from Busines to Economy. i.e. J C D I, then Y B H. BA has W and T (the fare buckets for Premium Economy) in between. Virgin Atlantic, also has a Premium Economy class, and those fare buckets aren't displayed either. I suspect it's a limitation of the underlying booking engine, rather than the tool itself, but thought I should bring it up.
And many thanks for making an excellent tool available to the FT community.