The rescue may come by EIB loan, outright purchases of (cynically: "investments in") Greek bonds by larger Eurozone members, or some other mechanism involving front loading of EU structural funds.
The next domino in the banking world (the Lehman Brothers of sovereigns) is the UK rather than one of the PIIGS. Who is coming tot he UK's rescue? (its not in the eurozone and its debts are totally unsustainable) Pimco, Soros, Rogers and others are on record with colourful language about the UK gilt market though one must naturally dilute their rhetoric by their book positioning.
Apart from a now failed banking sector it does seem tough to establish what the UK actually does, makes, owns or controls that will provide the earnings to save it from a debt crisis.
Simplistically, what does the UK actually do from the viewpoint of a foreign debt investor with an itchy sell finger? Is it bereft of value or does British modesty cause it to hide its light under a bushel?