I think the polished brass one might have been what they called the 'Millennium' edition - it might also have been one of the 500 series. I could be wrong - I didn't ever have one and it's a while ago now...
Warming to Tilleys now, and I'd like to start collecting a few older ones. I'd like to get my paws on a Pork Pie soon, if I can find a semi decent one. I'm afraid I don't have the room or facilities to do full blown restorations at the moment.