I don't know if this is considered reanimating a zombie thread, but I thought it better to have all the posts about one movie in one thread. Apologies if I have made a grave error.
This movie opened last week in Canada. As a huge Iannucci and Isaacs fan, I had high expectations. I was not disappointed.
Simon Russell Beale was outstanding. I've heard that he is a respected stage actor but I think I have only seen him in a few things onscreen, Persuasion, being one, MI-5, another. He was so good, along with Buscemi, that I didn't mind (much) that Isaacs wasn't around for the first bit.
As for Jason Isaacs, in addition to Case Histories, already mentioned, above, I suggest you search for Brotherhood and The State Within. Bonus fun, The Patriot, (just slip away to make tea whenever Mel Gibson is on the screen).