I think this about myself all the time: Who is it who answers when someone calls "Cat"?
I've changed so much - at a biological level, I've grown fat, aged, the cells in my body have changed enormously; my personality has changed - would child-cat even recognise me as a friend, let alone the same self?
Likewise, I guess, "England".
Change and identity are tricky old things, aren't they?
I guess the people who say this are mourning something they think has been lost and objecting to something they see in the present. I suspect you have a good idea what that might be.
For myself, I rather miss the decline of social mobility and a belief in the value of public goods.
I suspect that people who use this phrase don't tend to mean to mark the passing of this. I wonder why people like me don't grab hold of the name "England" and try and seize its meaning a bit more.