The Tories like to argue that they are strongly against nationalisation as a principle, and I would agree with them on this, but there are times when nationalisations are necessary and can work for the company, the customers and taxpayers.
Ignoring the Tories own nationalisation of Rolls Royce Aero Engines (now privatised, profitable and still British), one of the Tories heroes was responsible for one of the biggest nationalisatiions ever when in 1984 Ronald Reagan authorised the nationalisation of the Continental and Illinois Bank.
The Continental and Illinois had taken on too many bad debts, suddenly had a liquidity problem and $10bn was quickly withdrawn by account holders. This meant, in a strange parallel with the Northern Rock, that the Federal Reserve had to step in and act as guarantor to the C&I, for the very same reason that Northern Rock had to be saved, put simply it was too large an organsiation to let fail and the implications would have been massive for the US economy.
The US government at the time sought a private sector takeover and looked in to this for two months, again, another strange parallel with the Northern Rock, before it was finally nationalised.
The US government finally sold off all its interests in Continental and Illinois in 1994, although it had effectively sold out the majority before then, and what might be of interest to people is that the US government made back all its money and made a small profit too.
So there is some hope that this can be done with Northern Rock too and it shows that even Conservative free marketeers know that sometimes you have to do things that go against the grain for the better good.