You're attacking my point without attempting to correct it.
you can legally discriminate if there are objective reasons for doing so
There is a ridiculous breadth of methods to legally discriminate. Equally, there are a large number of ways to fall fowl of the law. I've highlighted one of those ways, and provided citation.
The rule of thumb when it comes to employment law is to always err on the side of caution. That's exactly the suggestion I'm making.
Also: I am an "approved" person within the meaning of UK employment law ie I could represent you at an Industrial tribunal
I am also an 'approved' person. As are the majority of tax paying UK residents.