Thanks for the replies, much in line with what I had read. It's interesting that the mainstay appears to be computer based but the CAA notes on becoming an examiner are that you must be prepared to travel within your area and not be solely one site based, I suppose a couple of laptops would do it. I recall seeing examiners using various radio/intercom based equipment and it was more that, that I was was looking for.
I understand all the limiting factors like, number if examiners in the area, CAA indicating they are not taking new applications etc, but I would be happy to start the enquiry if I knew the equipment, or some means of building it, was available.
Many thanks for your valuable insight.