Well I don't think it's fair to say that it makes no sense - one of the criticisms of the Eurozone is that it robs individual countries of having individual control over their monetary policy, where less developed countries (or at least those who saw the greatest levels of asset inflation during the boom times - Greece, Spain, Ireland etc) might want a "weaker" Euro to boost their exports where as more developed countries want to keep it stronger to make imports cheaper (which obviously works out very well for Germany, being both a highly developed economy and one that exports a lot, whose currency is weaker than it'd be independently, but strong enough to keep foreign imports relatively cheap).
So for those who want to see British exports grow and see a potentially weaker pound as a route to reindustrialisation in parts of the country that were made effectively obsolete in the expansion of globalisation that ramped up in the 80's, it makes does make sense. In fact, it's almost monetary dogma (devalue currency during a downturn to make domestic production more competitive for your people and your exports more competitive abroad). Whether it will work in the UK is another matter, since most of the industrialisation that still exists in the west relies heavily on foreign imports (unlike, say, making something in China where they have large volumes of domestic steel production). But given how much of our economy is reliant on services, most of which don't require much in the way of imports, I don't think it's fair to say that it makes "no" sense. It's just... questionable.
