Irresponsible???
The CAA has made it clear they have no planes to make Transponders compulsory in all UK airspace. If a qualified pilot chooses to fly a non-electric aircraft the length of the UK with no radio and no transponder he is allowed to do so. I know several people who flew from the south coast to Wick is such aircraft least summer. This is not irresponsible at all. There are far more flying machines with no transponders in the UK then with.
The CAA position is that if a VFR pilot chooses to fit mode s they will have more straightforward access to some airspace. Do not try to demonise the majority of pilots, a Transponder is not ever going to be fitted to an unregulated 115kg machine, but sales of such are likely to be an order of magnitude more than traditional GA. The traditional single engine C of A fleet is about 7000 strong. 12000 paramotors were sold in the UK in 2006. In total there are about 4000 micros, 1000 LAA machines (without transponders) 4000 gliders, etc etc etc.
Rod1