Another problem, anyone ever been in this situation, you're doing 70 and suffer an engine failure (or just run out of petrol, so you jump into the hard shoulder, put your hazard lights on and coast to a junction or the next services or whatever.
I've done it a couple of times, on one occasion when I was younger and stupider I managed to coast from just after one junction, come off the next junction (which was a downhill) through a roundabout and into a petrol station (only to end up on the wrong side of the pump

) . A more sensible person would probably aim to coast to the next emergency phone as that's safer than walking down the hard shoulder. Under this new scheme I'd get a nice fine for using the hard shoulder without paying.
Firstly, getting into the hard shoulder once broken down and coasting is going to be difficult as you'll be moving from the slowest lane into the fastest lane, there's a good chance that you wont be able to get in at all and will eventually come to a stop in L1, creating massive queues as all the lorries try to overtake you, and a good chance of being rear ended (though the chance of being rear ended if you actually make it to the hard shoulder is probably higher)
Secondly, if they're reading your transponder, it wont be long before they start measuring your speed ala SPECS and fining you for going over 70, who is going to pay to use a lane where you're at increased risk of a fine and points, overall it's probably going to be quicker to risk using L3 if you're a habitual motorway speeder. This isn't a problem in America because "everyone was going that fast" is still a valid defence and you're more likely to get pulled for going slower.
Lastly and it's been pointed out before, toll lanes and HOV lanes only work in america because they're a couple of lanes on a 10 lane highway, so the reduction in capacity when you convert the outside lane is only 10% not 33% like it would be if they tolled the outside lane of a UK motorway. Even so the HOV lanes (in California at least) are still problematic there thanks to them allowing the Prius into them, most folk like to do 85mph and then they all bunch up behind a Prius doing 60. I also hear that the hitchhikers around the start of the HOV lanes are now charging drivers to give them a lift!