It's been a long time coming, but wild bison are being reintroduced to Britain right now:

https://www.kentwildlifetrust.org.uk/projects/wilder-blean

https://www.rewildingbritain.org.uk/why-rewild/reintroductio...

This is mirrored by reintroduction schemes of red kites and beavers in the UK, as well as similar projects with bison, wolves and other species on the European mainland.

That's not to mention deer, which are both wild and doing really well - partly because of the lack of wolves, ironically!