The UK can print as many or as few pounds as their situation requires and the Bank of England can move interest rates in conjunction with the UK's needs while the ECB has to do it for the whole Euro area (despite dramatically different needs between regions)
but, they can't. they could, but then the trust in the coinage would drop. you can't just pancho villa your pound, print a ton of it and expect it to hold its value.
when i was 17 (i am now 43) i went to london for a week. there was a pub at the corner of tottenham ct road and oxford street, the flying horse. a pint of guinness was £1.85.
that pub is still there.
https://www.google.co.uk/maps/@51.5...00&yaw=266.99048&pitch=0!7i13312!8i6656?hl=en
today, a pint of guinnes is £3.40
back home, in the same period, a can of coke was 400 lire, or 20c today; today it costs about 1.5E, seven times as much.
a pack of camels was two pounds fifty, which was enough to buy three packs of the same back home.
England was legendary for how expensive it was; and yet, they still got massive trade from all pre-euro countries, due to their political importance. We traded with them despite the cost of buying the pound, because the UK was seen as a postwar leader.
Today, euro countries still buy from the UK, and that is not a surprise, because the pound is costing less and less; at one point the Zloty went from 7:1 to 4:1. We went from 1:1.5 euro to 1:1.1, and sure the markets fluctuate, but it's because the currency becomes more used in trade when it drops in price.
This has an internal effect; brits cannot afford to go abroad on UK wages anymore, when once they dominated the continent with their awesome exchange rate (at one point, 3200 lira per pound, or 1.6E equivalent). Their economy is based on having a strong, expensive coin, not a popular and cheap currency with much external movement. It is, if you will, "their money".
And that is also why they suffer more when capital migrates - they have less of it. Just five years of wages moving to the continent have had a devastating effect on the economy; you go back to the 90s, people were throwing £20 notes around like it was nothing, today that same note is a £5.
As a country, they managed to earn more because trading with them had an additional perceived value due to their political importance - which they no longer have.
If the pound had kept its perceived value, i would be earning nearly £2k/ month, and i would not have a problem paying £800/mo for a room in london. Instead, i'm earning barely 1k and the price of that room is still near 800.
1990 values would be, £160~180 earned a week, cost of housing £60/w.
It's not the state of the economy as a whole, but that portion which the public perceives, which matters to the voters. They don't care that Tesco is posting more and more revenue, if the public never sees any of it.