In this excellent short book, Dalrymple suggests rather strongly that Mr. Clarke's proposal is nonsense: his proposal is to release a lot of criminals from jail (to save money) and to place our bets on rehabilitation (which is right up there with tooth fairies).
Dalrymple adopts the very clever tactic of reporting the crime news from a town called Yeovil, in Great Britain. Simply by doing that, he makes it abundantly clear that Mr. Clarke's proposal is nonsense.
American experience offers support for this obvious idea, because we had to suffer through the ultra-liberal Warren Court doing the same exact thing --- releasing criminals and betting on rehabilitation --- with disastrous results, finally leading to Nixon campaigning on a "law and order" platform, and winning.
The only "rehabilitation" which works is locking crooks up until they are old. Sad, but true. Flying unicorns may apply elsewhere.