There are many amazing Richard Thompson songs spanning a very long career and a variety of styles. I leave it to you to decide what would be best for this site!
His hybrid technique of using a flat pick on the base strings while finger picking the others would be a great skill to work on.
If you know of a song that you think would make a good lesson, here is the place to bring it up. As of May, 2015 we have over 800 song lessons but are always on the lookout for more. Be sure to point out what about the song makes it a good candidate, unique or unusual, a particular part that interests you, or just that you think a bunch of members would enjoy it. An embedded video would be helpful as well.