Brexit is an identity marker, not a progress determinant. And not British identity but English identity. The Union might even collapse.
And as for England being the 'New Jerusalem'.. Doesn't quite fit does it? English nationalism does not have anything of the progressive potential which smaller nationalisms fighting against larger oppressive political states can often have. English nationalism is the larger oppressive nationalism.
English nationalism is the means by which conservatism displaces the anger and discontent which its own economic policies produce, onto a series of scapegoats. In recent years the EU and economic migrants have been those scapegoats.
You ask if this is progressive? Do you view yourself as a consumer or a citizen?