British pound and US dollar heading towards parity

The Guardian has a story today about sterling's possible parity with the US dollar following a hard Brexit.

Fact is, measured in purchasing power, the pound has been close to parity with the US dollar for years. Any American and Canadian tourist can tell you that British prices in pounds are in the same range as US and Canadian prices in dollars. Which makes the UK an expensive place to visit, and a very expensive place to live. No wonder so many Brits are fed up with their politicians.

So why has the exchange rate exceeded the domestic purchasing power of the pound? The UK's refusal to use the euro is the usually cited culprit. But that isn't a reason, it's a consequence. The root cause is the pound's role as an international currency, along with the US dollar and the Swiss franc. All three currencies are used for money laundering.