Chris here.
Came across this group while checking out and researching stuff concerning 'The Extreme' r/c submarine on GOOGLE; as one does. There was a picture of it plus a yellow DSRV sub and a steam turbine sub taken a few years back at a Kempton Park show. I had borrowed these for the show from my good friend Nick Burge. The Extreme model I still have today and is I believe one of only 3 hulls ever produced. Nick had built it (with Dennis Caters hull) and it was originally set up as a static diver but he tried it as a dynamic boat module too and it was found to perform just as well so that's how it is now.
The DSRV mini sub and the steam turbine sub I later sold and the proceeds went to Geraldine (Nick's widow by then). I bought the Extreme for myself. That actual DSRV features in the film "Sub Down" hence its odd shape as that's what the film company wanted!
These days I have got back into R/C boats as have been busy with personal hovercraft and stuff for a while.
Interests are model boats of course, as in fast electrics, subs, yachts, airboats and my model tanks (like a quarter scale German Panther tank that tips the scales at over a quarter of a tonne)!!!
Cheers