Simon's gold vest was worn in a photoshoot. I'm actually not sure if it was worn in an episode.
More pictures after the break...
More promo pictures:
So, my task to you...FIND THIS VEST! :) Maybe it was just worn for this photoshoot and not used in an episode. Maybe it was and I just totally missed it. Good luck!
ETA (3/18/2013) FOUND IT! It's in The Train Job:
My Photobucket Album for Simon.
Serenifly Costumes site for Simon.