Putting Barset and Palliser aside, Trollope turns out to be quite a rare author. Posterity has whittled his enormous output down to a core of fewer than fifteen texts. These are regularly reprinted and everything else falls by the wayside. This happens to a lot of "classic" authors. Sometimes understandably. You'd have to be very keen on impis and white goddesses and African curses to want to plough through the whole of Rider Haggard. King Solomons Mines and She are the essential texts- and everything else is just more of the same. But Trollope is a different matter. I haven't seen it suggested that the neglected texts are inferior carbon copies of the favoured ones. It's just that there are so many of them- and posterity is lazy.
So I'm setting myself the task of hunting down the "lost" Trollopes. I've done it for Chesterton (who was hideously prolific) and I'm concurrently doing it for Wells. I could use the internet, but I don't think I shall. It's so much more fun to poke about among the stacks.