Thanks for all the ideas guys.
I don't think the bike is based on a traditional road bike - the top tube slopes down like a mountain bike etc.
The actual bike I'm talking about is a Giant Great Journey - seems to be made only in Japan. You can find more details here
http://www.giant.co.jp/2005/index2.html
Click on Products > Adventure Bike - Great Journey > Specs & Enlarge Pics > Specs & Geometry.
Nearly all the info should be in English.