Its the Nimbus round crown frame. Since you are across the ocean you can get it here:
http://unicycle.uk.com/shop/shopdisp...?catalogid=672
It says for 40mm bearings but the build tolerances are low enough that it fits 42mm just fine. I haven't had any problems with it at all. Its a nice light, rigid and low cost frame. Excellent deal if you are doing trials.