Thanks for your interest Stuart, much appreciated.
Unfortunately, the bar for later cars is very different, not entirely sure why to be honest, but presumably there is a good reason.
Also, you may well be right about lpg, as I was knocked back by a local mobile fitting company, because of it.
Asked him why and he "wasn't sure", that was the end of that conversation!
I will be pulling a heavy caravan if I get one fitted, though probably only a one off trip from Sussex to Devon, where I'll be storing it.
Not sure how keen they are going to be at mot time either, as post 98 cars fall under stricter rules I think, but I'll worry about that if/when I get there.