So it is Citi to the rescue. The world's second largest bank has apparently expressed interest in extending credit to Northern Rock. With the world's eyes on the troubled UK lender, this is a cracking opportunity for Citi to advertise the advantages of its size and scale.

In fact, not even a bank the size of Citi would be capable of refinancing Northern Rock by itself. Citi will have to bring in partners. Moreover, it will not be possible to finalise terms until there is clarity over the future of the government guarantee backing Northern Rock's depositors and senior creditors.