The main problem with the proposed law about banning these XL bulldogs appears to be defining exactly what a XL bulldog is, given that so many are part one thing, part another. All that's going to happen is that the irresponsible owners are just going to argue that their dog is something else, and it's going to cost a fortune in kennelling and legal fees while it's all decided.
Wouldn't it be simpler and fairer to come up with some sort of law that says that dogs over a certain height/weight are restricted - they must be chipped with owner's details regularly updated, must be muzzled in public, must be neutered unless you have registered and paid £££ to be an official breeder, must be kept on a lead at all times etc etc etc. It's then far easier for a police officer to whip out a tape measure or scales and say that this dog is either covered by the law, or not.
Yes it would affect people like the woman who lives near me and who has two large Newfoundland dogs which don't appear to be aggressive at all but it's certainly clearer and easier for public and police.