Sadly, there's only one answer: nationalisation

Even when their surveyor reports a bit of subsidence, they seem as keen as ever to exchange contracts. But then the delays begin, phone calls are not returned, their solicitors get blamed for going on holiday, until after months of stalling they suddenly pull out of the deal. It turns out their building society discovered dry rot in the attic and won't lend them the money.

Given how difficult it is to sell one house it is a bit hard to complain about the time taken by Northern Rock's board to sell one severely compromised mortgage bank with such an acute problem of subsidence it would have slipped beneath the waves had the Bank of England not agreed to keep it afloat.

But by common consent everyone is now heartily sick of the saga and wants it resolved. Northern Rock may not have lost the will to live but people waiting for a resolution of the crisis are beginning to.

If the crisis is to be resolved, someone is going to get hurt. Today's shareholder meeting in Newcastle is a pretty pointless exercise other than in proving that the two hedge funds leading the agitation have the power to force the board to call a meeting and by extension give further credence to their threat to derail any plan that does not give them what they think is fair value.

But in reality, while they may have the power to block, they don't have the resources to build and their complaints take us nowhere nearer a solution that will be acceptable to all the parties - shareholders, possible new owners, creditors, the Bank of England, the regulators and the Government.

What does seem apparent, though, is that the chances are fading for a successful private-sector bid either from the Virgin consortium or Olivant. The attraction of the private-sector deal has always been that it would bring in new money which would allow the Bank of England to get some £11 billion of its money back immediately. However, the continuation of the credit crunch has dented the always-grudging willingness of private-sector banks to put in new money, other than on eyewateringly expensive terms - so it is proving almost impossible to nail down a watertight financial package acceptable to all parties.

This may not be altogether a bad thing, however. While the attraction of a private sale was the promise that the Bank would get half its money back now, that comes at a price. The unspoken risk is that it would in effect have to whistle for the rest of its money because the new loans would almost certainly insist that the old loans got pushed to the bottom of the pecking order for being repaid.

It took 20 years to tie up all the loose ends of the Johnson Matthey bank rescue, launched way back in 1984 - which goes to show all too clearly how being last in line in a bank rescue is not a good place to be.

The time may be fast approaching where the Rock's board will have to give up on the private-sector rescue and give serious thought to the only other possible outcomes. If the bank is to survive, it will have to be nationalised; if it is allowed to die, then it goes into administration.

People recoil instinctively from nationalisation because it conjures up images of British Leyland in the 1970s, with folklorish memories of workforce anarchy, lousy products, general managerial incompetence and waste.

But it does not have to be like that. A majority of BP shares were owned by the state for nigh-on 50 years and it did not do the oil giant any harm. The trick is for government to own the business but not to try to run it. A nationalised Northern Rock would still have a professional board and executive. It would not be in the hands of civil servants.

Nor would the intention be for the state to hold it for ever. Rather, when it had been stabilised and returned to profitability, it would be sold - as has happened on several occasions with bank rescues in countries as diverse as Sweden and Hong Kong - and in stark contrast to the other solutions, the taxpayer would get the profits.

That would, however, be difficult to pull off because in this country governments are not allowed to go round seizing assets. A three-line law could be passed giving the Government power to act but it is still either going to have to agree a price with the shareholders or risk being sued by them - as Railtrack shareholders sued a couple of years ago.

Paying the shareholders for a bust bank will stick in the craw; not paying them risks huge embarrassment in the courts. Chancellor Alistair Darling is indeed caught between a rock and a hard place.

Then there is the further, not inconsiderable-disadvantage that it may not get back to profitability after being nationalised. The malaise in the housing market makes this the worst possible time to get into the mortgage business and it may be the Northern Rock brand is so damaged that it proves impossible to rebuild the business. Northern Rock changing slowly into White Elephant is the stuff of political nightmares.

However, the only alternative is administration - and that is every bit as ugly, even if in crude business terms it looks the logical thing to happen. But even administration is complicated because the act of administration would immediately freeze all the assets - making it impossible even for account holders to withdraw their money unless the Government renewed its promise to cover any withdrawals.

It is complicated, too, because much of the mortgage book is not technically owned by Northern Rock - thanks to its policy of securitising its mortgages. So there are issues about how the assets of Granite - the securitisation vehicle - might be drawn into the net. And of course almost all the jobs would go because the bank would most likely cease to trade and go into run-off - so there would be serious political fallout: all that Bank of England money put at risk and still no jobs saved.

There is no easy answer and arguably no answer at all to this conundrum. But it is the job of politicians to reconcile irreconcilable differences, and that is what Alistair Darling is going to have to do, through nationalisation, if there is to be any chance of pulling £20 billion of public money from the Northern quicksand.