The UK had its own currency and central bank from the get go. What are you're referring to exactly here?
Populism is going to cost the UK dearly. And not just in terms of money. The UK is heading headlong into a kind of society taken straight out of the pages of "V for Vendetta".
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[1] "Controls on immigration"
I call "Godwin by Proxy".
There's many reasons to fear current trends but it's a touch premature to predict we're about to become a fascist dictatorship.
[1] as in, not funny at all
Yes, but if you are officially retailing in the EU you are obliged to adhere to EU warranty regulations, to EU safety regulations (flame retardation etc.), you must charge VAT (and pay it to the EU), etc. etc.
Similarly with fiscal policy, whilst the UK is supposed to "endeavour" to follow the Stability and Growth Pact rules on keeping deficits down, it can and does cheerfully ignore those rules without risk of penalty.
Actually it was a bureaucratic plan all along, and badly managed.
And you still can have great access to the same 320 million market even outside of it (like e.g. China or Japan have) -- with the extra benefit that you don't have a German-controlled ECB to impose you rules and monetary policy.