By Zara Woodcock The Crown star Dominic West said his wife Catherine FitzGerald told him he “isn’t very good” at playing posh characters on television. Dominic, 54, who went to Eton when he was growing up, revealed that his “upper class” wife told him he isn’t very good at playing posh characters on screen. The actor is most recently known for his role as Prince Charles in The Crown. “My wife, who is genuinely upper class, always tells me, ‘You’re much better in the working-class parts, you’re not very good as upper class, you’re not convincing at all,’” the star told The Sunday Times. The act…