There was always a group of top German economists - call them the Bundesbank tendency - who had deep misgivings about the whole single currency project. Now some of these German sceptics believe their concerns are being vindicated and are even suggesting that - despite the current calm in the markets - Greece may have to leave the euro within months.

One scenario doing the rounds in Frankfurt and Berlin is that the crisis could be provoked by the Greek elections, which are likely to be held in early May. A new Greek government might seek to unpick the latest debt deal, provoking a chain of events leading to Greece leaving the euro. Technically, it is said that this would involve the sudden declaration of a temporary bank holiday, during which all euro-notes in Greek banks are stamped, to show that they are being reissued as drachmas. One obvious danger is that - as soon as this step was announced - there would be bank-runs in other vulnerable euro-area countries such as Portugal, as anxious account-holders rushed to move their money out of the country. This would be counteracted by the provision of massive emergency liquidity from the European Central Bank to financial institutions in vulnerable countries.

Doubtless, there are many flaws in this plan. But the very fact that such stark scenarios are doing the rounds in Germany may help to account for Chancellor Angela Merkel's recent decision to give interviews proclaiming her belief in Greece staying inside the euro and suggesting that the single currency's break-up would be a political disaster for Europe.