It is all very simple but some people are either not reading or understanding so I will try to explain. "Beasts of the chace(chase)" were every and any animal that people wanted to hunt and kill. Eventually the word "vermin" was used to mean the same thing; animals of any type that were preferred for hunting. It is only hunts and supporters that use that term and it has never officially been used.
Seals, sea lions, cormorants..well, open any illustrated natural history book and point to a bird, mammal of any type and it was for killing. Authors wrote of seeing a seal resting on a rock and noticed it was within shooting range. So moron took his shot and the seal tumbled into the water and sank. Shooter had no idea if he had just wounded or killed it but simply got up and walked along to see what other shooting there was to be had.
Not just gentlemen but !lower classes" could take part in killing wildlife and earn enough for a boozy night or feed the family -foxes (adults and cubs), badgers (ditto), hedgehogs, pine marten on and on the list goes. Why kill these animals? Because they were not wanted as they fulfilled no practical function for humans...other than 'sport'.
By the 1860s Old (original) British red squirrels were wiped out with only one or two pockets continuing. Yes, people DID care because no red squirrels meant no fun shooting. The solution -import red squirrels from Europe. Since the 1860s the red squirrel has faced several near extinctions and nothing to do with grey squirrels. Even today this 'protected' species is shot on private estates and trapped, shop or killed in other ways by commercial forestry companies. None of those ever faces prosecution or any type of legal kick-back but the grey squirrel is a fine scapegoat.
By the 1860s hare coursing had wiped out hares in England. The whole 'sport'of hare coursing along with hare hounds faced it's end. There was a solution: import hares from Europe and so hares flourished again only to be nearly wiped out and today the number in the wild is not that great.
In other areas deer hunting wiped out the species and a solution was found to this: import deer from Europe. Of course, those deer were hunted until their numbers dropped then more were brought in.
The three types of Old British fox were written about in the 'sporting' journals and books. Everyone stated that these foxes were becoming extinct. They kept hunting until by the 1860s the Old foxes were gone and replaced by foxes brought in from Europe, possibly starting in the 1700s. There have been several massive falls in fox populations since the 1900s and we are currently looking at another that may well lead to extinct in the 2030s.
Wild cats were also 'sport' and by the 1860s -a period in British natural history worth noting- the true Scottish wild cat was extinct. Naturalists who had also hunted these animals noted how museums they visited had taxidermy 'wild cats' that were not. The type currently used as the "poster animal" for the species only started appearing in the late 19th/early 20th centuries and there are photographs proving the point. We know that menageries and zoos wanted wild cats and the many animal importers were willing to supply. There may have been some escapees but their distribution and the hybrids they produced are a puzzle until recently when my research discovered that owners of hunting territories were restocking those areas with wild cats so that those with licences had something large to kill.
It goes on and on and on ad infinitum.
Shooters are currently chatting about where wild cats are going to be released and the excitement over when wolves or lynx will be introduced is high. Yes, bring them back and they will be wiped out.
The wild cats that currently exist, as I have pointed out so often, are not "re-introductions" because you cannot re-introduce a species that went extinct in the 1860s -none exist. These are introductions to fill in a niche the original extinction left almost open. Note that even now the 'protected' wild cat is still being killed on farms and private estates because there is no strong arm law to prevent this. Do you really think that wild cats wandering into a private estate are going to be allowed to do so?
Introductions create other problems. Some wild cats are due for release in areas where the pine marten has returned over the years. Two predators in a geographically small area...not a good idea.
When you read that DNA from UK wildlife matches European species it is because they are that species. We need really ancient bones, etc. to try to find genuine Old British wildlife DNA.
Summarising:
A died out so A2 imported from Europe
B died out so B2 imporeted from Europe.
Just continue with that until you come to Z