Q Are people right to say this could be the next Lehman's?
It certainly could. As is the case in every country, Greek banks' balance sheets are heavily invested in the country's government debt. Should that debt suddenly be worth half its face value, the Greek banking system would become insolvent overnight. This, in turn, would trigger major losses for some of Europe's biggest banks, some of which, particularly in France and Germany, are perilously undercapitalised. This threat may explain the ECB's reluctance to countenance even a soft default.

Q Does the Greek situation make the collapse of the euro inevitable?
It raises major existential questions for the euro project – and not merely because the straitjacket of euro membership has so limited Greece's options in responding to the crisis. The major counter-argument to the euro was that it is impossible to have a currency union without a fiscal union. In other words, without a central authority with the power to tax and spend, it is impossible to get an area as large as the eurozone pulling in the same economic direction. And that was what came to pass: over the past decade and a half, Greece and many Mediterranean neighbours (not to mention Ireland) have borrowed and spent too much while Germany has saved too much. The idea that such divergent economies could issue currency that was supposedly worth precisely the same value everywhere is unfeasible.
It is difficult, in economic terms at least, to imagine the euro surviving in its current state – particularly because Greece's problems are shared by other countries. Granted, the euro is a political project. But the scale of anger in Berlin at the prospect of having to transfer billions to its Mediterranean neighbours purely to safeguard the euro project is such that it makes stark the question of whether there really is the public will to keep it alive.

Q What does this mean for Britain?
While Britons can allow themselves some smugness that the country did not join the euro, and so was spared direct involvement in the crisis, the implied risks for the UK remain significant. The threat of losing money through IMF loans pales into comparison with the broader impact a Greek economic collapse could have on the UK economy. Europe is the UK's biggest trading area; a crisis would undermine British exports. Moreover, the collapse of Greek finance could well trigger similar implosions in Spain and Ireland, both of which have intimate links with the British financial system. More generally, any sort of sovereign default would raise further questions about highly indebted, deeply imbalanced economies around the world. No prizes for guessing which green and pleasant land falls into this category.