Hi, Our12.
There is no requirement to have the roll bar bolted in the car for the VASS certificate, or engineering if required. I had taken it out as I prefer the look, however, subsequent to selling it, I have bolted it back in.
The soft-top works by small pieces of tube called hood-bows. These attach and swing up to make a tent-like frame. The roof then buttons on to the body work and voilà... Weather protection!
There are some photos below that show the car with the roll bar in place (sans windscreen), with both the roll bar and the hood bows in, and with the half-tonneau on.
The car did spend time in Japan. It was first manufactured in the UK at the Caterham factory, and was then shipped to Japan and bought by a Gentleman in Hamamatsu who used it for Club runs. I bought the car in Japan some years ago from his wife, after he passed away and drove it for a while.
I brought the vehicle into Australia in 2007.
Appreciate your interest shown.