Sterling has been a fiat currency since WW1. So it's survived about 100 years.
Churchill was very anti fiat currency, I believe. He tried to put us back on the gold standard , but at the pre WW1 price , and brought deflationary havoc as a consequence.
You could argue that since WW1 sterling has traded against the dollar which was until 1971 on a gold standard thus that we have only been totally fiat since 1971.
Since 1971 we have had two major currency crises and devaluations.