Versus the alternative.
As the rest of the world pull ahead in manufacturing and British businesses are suffocated under a vastly overvalued pound (Valued against gold, which Britain doesn't have anymore) this affects every area of industry, from mining to high-tech manufacturing, to finance. As one exporter closes down, so do the vast numbers of businesses which support them from below.
Wages continue to drop as the companies have to mak more and more from a shrinking sales until they simply acn't afford to keep staff. mass layoffs are seen and unemployment rises, crushing demand and drawing more and more companies into the hole.
Of course, less money being spent means less taxes gathered, the government is faced with only one option when the business environment is so bad, and that is to raise taxes, further stagnating demand. Public services are cut again and again and again as we cannot ease our debt demands, including front line services like the police and armed forces.
Tempers flare among a growing unemployed community, crime skyrockets as services are withdrawn. Protests become riots, riots become commonplace. Those who can afford to leave do so, killing upper-middle class demand.
Assuming the government continues on the gold-standard letting the pound become more and more overvalued as the output of Britain keeps falling, prices for essential goods continue to rise, despite the quality of goods falling. Local areas adopt new local currencies to pay for goods prooduced in the area as the pound becomes too valuable to actually spend, these new divided currencies help for a while as local areas can produce their own little inflationary bubbles to keep costs down until these currencies too become worthless against the pound.
The government is forced to curb civil liberties to keep control of its increasingly angry citizenry, armed forces try to contain riots and rebellions occuring all over the country. A crisis point is reached, either the pound is abandoned and the government jumps on the nearest currency not currently hyperinflating or face civil war.
Bang, we're back on a fiat currency except without the power to actually control it ourselves, all the fears of hyperinflation are exacerbated by a country where the infrastructure and social glue has collapsed.