NEW YORK — He is the slick and smarmy servant whom “Downton Abbey” addicts love to hate. Thomas Barrow — as played by Rob James-Collier — cooked up schemes such as selling food on the black market and getting his hand shot at to escape active duty during World War I. He regularly joins forces with icy O’Brien (Siobhan Finneran) to try to get poor Mr. Bates (Brendan Coyle) tossed out of the Abbey. But James-Collier defends Thomas as misunderstood, not evil. We were skeptical, but pressed on for details.