If you want to go the authentic route, and excluding a Kirkham, the best in the UK is a Crendon (but perhaps I would say that).
The Crendon chassis is true to the original twin drain-pipe design, but also benefits from a number of subtle suspension geometry tweaks, which means it also has excellent handling, even with a BB fitted.
Lots more on all the UK offerings at
www.cobraclub.com - feel free to come and introduce yourself.