I am not applying anywhere, I am not even a UK citizen.
These questions were just out of curiosity as I'm interested to know about the different systems of education around the world.
I read somewhere that these interviews are not confined to private school or independent school admissions, popular grammar schools also hold interviews, is that correct ?
No Grammar schools don't interview - if you are abroad then you may not realise that not everywhere that is called a Grammar school is actually a selective state school. Some with "grammar" in the name are actually non selective and some are independent schools.