What type of flower forum, was it single?

Because there are thousands of red/near-red roses. Take a look at the FAQ page for this forum, and try to answer as many of the questions there as possible for the rose that you saw. It might help narrow it down.

There is also the "Advanced Search" feature at helpmefind.com, which is a large database of roses. You can start off at "Bloom".

Here is a link that might be useful: Advanced Search at Helpmefind.com

Could it have been Paul Neyron? It's blooms are known to be very large. There are pictures on this thread posted to the Antique Rose Gallery:

http://forums2.gardenweb.com/forums/load/rosesant/gal1018560732050.html?6

More pictures on the link below:

Here is a link that might be useful: Paul Neyron at HelpMeFind