How can there be an episode where Timothy Hutton has to dress up as a literary detective and he doesn't go as Archie Goodwin. What a waste of a premise! Aarrgh! (Sorry I had to vent somewhere. No one else I know IRL watches this show.)
I watch Leverage online. I haven't seen the episode you mentioned. Based on the premise you've described, the only right answer is Phillip Marlowe.
Well, maybe that was a no brainer, but did you know his father played Ellery Queen in a short lived series? It was a homage to his father, Jim Hutton
I knew he was doing Ellery Queen as soon as I saw him coming down the stairs to meet Sophie. Not sure about the sweater, but I'd lay odds on the hat. You know, the one season, complete series of Ellery Queen is available on DVD, it's still a lot of fun to watch. Edit: Here's the intro to [WYT="The Adventure of Auld Lang Syne"]ervzicH2AMY[/WYT] Lots of great guest stars, even an early Nero Wolfe in the cast!