Michael Sheen - AP Photo
For whatever reason, Sheen and Ferguson have an honest rapport with one another that makes for good TV.
In Sheen's latest appearance on the show, he went on to promote his new film The Special Relationship in which he reprises the role of Tony Blair, former Prime Minister of the U.K.
The film debuts tonight on HBO (at 9:00 p.m.), but you'll probably find that in this interview, the focus of the discussion is quite apart from the intricacies of the picture.
(If you're interested in seeing a trailer from The Special Relationship, see here.)