Regardless of whether we are in the euro or not, regardless of the fundamental reasons why Greece is in such a poor financial state - The UKs own financial self-interest dictates that we should be involved in some sort of rewriting of Greek Debt.
For those people who are not fans of the EU and the whole european project, the looming spectre of a failure of the euro, with nations leaving, defaulting on billion euro debts etc might seem to be a good thing for the UK and sterling, and a vindication of their view that the EU project was too ambitious, too intrusive, too federalist.
The problem is this - UK banks have around £6.5 trillion invested in loans, with only £300 billion in security and cash reserves. Around £1 trillion of this is in euros, to various governments, companies and banks all across europe. Thats pretty much equivalent to the UKs entire GDP for a year. Should the Greeks be forced to withdraw from the euro and default, this could very likely cause similar defaults and a collapse of the euro.
We still havent received back the £2billion from Iceland as yet - It would be catastrophic to the UK were those loans defaulted on.
All financial systems are interconnected, and it probably is in our own national self interest to ensure that we participate in ensuring that the euro project does not collapse.