"The other issue here is that the CAA in their wisdom have approved non transponding gliders all the way up to 195. We simply can’t see them if they are orbiting as the radar filters them out thinking it is weather due to the low ground speed."
1. At those levels they are unlikely to be orbiting (as in thermalling), more probably in wave where their airspeed almost matches the windspeed so are almost stationary.
2. Even those gliders that are transponder equipped are probably breaking the law if they use them. Class 2 transponders (130 W) are approved for use up to only FL150 - above that Class 1 transponders (250 W) are required. I doubt that many/any UK gliders have Class 1 transponders due to battery limitations.
3. The non-transponding gliders above FL100 are only present in "notified Non-SSR Transponder Glider Areas" day VFR. When areas are not notified then non-transponding gliders will not be there. Notification by NOTAM is typically >18 hours in advance.
4. The emotive wording "the CAA in their wisdom" does not reflect the reality that the previous freedom to fly without transponders in Class G airspace has been progressively removed and that above FL100 is now possible in clearly defined areas and the further restriction of prior notification has been imposed only in the last couple of years.
5. Current CAA policy seems to be that gliders will soon need transponders below FL100 in most circumstances.