10 biggest export markets fell between the first and second quarters of the year. The main culprit, of course, is the state of the world economy. If demand for a country's exports is falling, making them cheaper through currency changes will make little difference. It also makes a difference which particular products a country exports. One cotton shirt is pretty much like another, and why not buy the cheaper? The same is not true for machine tools. The world has changed a lot since Harold Wilson was prime minister, and even more since these simple supply and demand devaluation theories were first proposed. Economists nowadays do see relationships between trade and "real effective exchange rates", where costs and productivity are combined. Work done by economists in the Central Bank has spurred similar exercises comparing EU countries by the Bruegel thinktank. The results are not always as expected, although Germany generally comes out on top, which is. Ireland is in the middle. It seems particularly poor, alongside Spain, at creating jobs. A lower currency may not be especially useful in its particular economy. It might be a bit more effective in Ireland, but there are two big caveats. In the event of an "Irlexit", where would a new Irish pound settle in terms of its rate against the new Germanic euro, sterling and the dollar? It would certainly not be under the control of the Irish authorities. The second caveat is what would happen to the important "real" rate. That would