
I dont think licencing would work - we already HAVE laws surrounding what you may and may not allow your dog to do and as threads on this forum show, it is not policed well enough.
Its another one of those things where the responsible who never cause a problem will comply, the irresponsible who cause problems wont do, and it wont be effectively or efficiently policed (because it wont be possible to do so as it isnt possible to effectively or efficiently police a lot of things), and the status quo will remain.
Anything that gets 'breed specific' is liable to backfire badly, as is the case with Pitbulls - before they were banned they were not particularly any more popular than any other similar breed and less popular than a lot of breeds. Now they are illegal they are effectively branded the desirable dog to have if you want to intimidate others!
Even if we DID manage to actually wipe out a certain breed in this country and prevent it from being owned/bred/brought in - people will do what they have always done...
Either, breed something similar from legal breeds - ie staffie x something else big and hard...
Move onto another breed - see Akitas/Rotties/GSDs/Dobermans/American Bulldogs/Mastiffs.......
Breeding similar dogs is sort of accounted for within defras guidelines as to what is or is not a pitbull 'type'.. ie, if it looks like one and one of our experts says it is one, then it is and actual genetics doesnt count.
I note no ones got crafty enough to breed a long haired pitbull... which is how the illegal dog of a few hundred years ago slipped through the net.... the coursing/poaching sighthound... crossed with everyones handy hairy farm collie... = ta da... stealth sighthound, in a collies hairy coat, meet mr Lurcher!
It doesnt matter what licences we have and what is or isnt banned - people will find a way round as theyhave done for thousands of years. Dogs are dogs and all dogs can be taught to look dangerous, behave dangerously, and to fight and if we banned everything wed end up with people paying thousands for fighting yorkies or protection JRTs! Theyd just have two or three at a time instead of the one!