Across the country a run on Britain's fifth largest lender after the Bank of England offers Northern Rock unlimited support.

Please wait while this video loads. If it doesn't load after a few seconds you may need to have Adobe Flash installed.

It certainly looks like a bank run - the scenes in London today fulfilled the dictionary definition.

And heading north to Nottingham, and Middlesbrough, the same extraordinary scenes: savers forming long queues to drain their life savings from Northern Rock.

Banking is an industry built on credibility, confidence and trust, but the Rock looks wrecked even in its home town of Newcastle.

Northern Rock in numbers 

- £113bn in loans and assets£24bn deposits,
- 1.5m savers 800,000 people who bought their homes with the help of Northern Rock
- £147m expected to be wiped off its profits
- 37 per cent fall in the shares today/

Economics editor Faisal Islam said: "Today's events are frankly unprecedented. This is no dodgy hedge fund or murky private equity company. This is the fifth biggest lender in the fourth biggest economy in the world.

"And the notion that savers up and down country would be queuing up to take out their savings is unthinkable, the stuff of financial nightmares, but it's really happening."

Deposit guarantees should prevent this. But even after an extraordinary unlimited lending facility granted by the Bank of England and agreed by the Chancellor, customers preferred the sight of real cash.

Financial revolutionary

From its roots as a sleepy building society Northern Rock has emerged as a financial revolutionary aggressively innovating in its mortgage lending and borrowing.

Despite its problems the bank is still solvent, it actually has half the proportion of delinquent mortgages on its books compared to other banks.

This is no bailout of reckless lending, but the chancellor turning back on a tap of funding for its business model that had been blocked off by the US mortgage crisis.

Chancellor Alistair Darling told Channel 4 News: "What's happened here is the bank is doing part of its job. It is ensuring that Northern Rock has sufficient finances to do its business n the normal way.

"All this stems from problems in the American housing market. What's happened is there's plenty of money in the system, the banks have money, but at the moment the banks are not lending to each other in the way they usually do.

"This has caused short term difficulties for Northern Rock. We want to ensure there's a stable banking system and that's why I authorised the Bank of England to make facilities available to allow Northern Rock to carry on doing business."

In the good old days, savers deposited their money with banks and building societies who then lent it to customers in the form of loans or mortgages.

But only a tiny proportion of the money Northern Rock lends comes from its savers.

Instead it's turned to the money markets - borrowing from other banks and financial institutions at market rates.

For years this business model has allowed Northern Rock to borrow cheaply - and in turn offer cheap mortgages - expanding its share of the mortgage business to nearly 20 per cent.

But fears about US mortgage debt have paralysed the money markets, causing the rate at which banks borrow from other banks to soar and many institutions to stop lending altogether - which has left Northern Rock's entire business model looking a bit broken.

"It's risky business if the wholesale markets either become a lot more expensive, or dry up, and that's what happened," Dr Willem Buiter, former Monetary Policy Committee member, told Channel 4 News.

"So they took a risk knowingly and they gambled wrong."

So now its the Bank of England offering a theoretically unlimited loan, at a penalty interest rate, secured against the value of Northern Rock's prime mortgages.

Talks had been going on for days. Channel 4 News understands that it had been borrowing its funding gap and rolling it over day to day. That was thought to be unsustainable when it appeared that stubbornly high interbank interest rates weren't coming down.

One bank's crisis is another opportunity, but there are at least three other banks that pursued a similar strategy, though aggressively, whose shares have been panned on the markets.

The Bank of England is clear today's action was taken not to save Northern Rock, but to prevent wider serious economic damage. It's done enough to keep Northern Rock trading normally for now, but it looks unlikely to survive as an independent company.

For the Bank of England this is just the beginning of an unprecedented challenge a tightrope between financial stability and undeserved lifeboat rescues.

Northern Rock's chief executive Adam Applegarth told Channel 4 News there had not been a run on the bank, but added: "We were certainly very busy today. You would expect after an announcement such as today you would certainly see a spike in volumes, and that's what we've seen.

"I'm sorry for our customers that are having to wait in order to be served, it is a busy time, but it is business as usual."

He said people could draw their money out if they wished, and added the business was also continuing to lend, but at a reduced level. He said the business was secure - one of the reasons why the Bank of England stepped in to help it with its "short-term liquidity crisis".

But there are questions over whether the politicians ought to have seen it coming, as Cathy Newman discovered.

"The message coming out of Downing Street is there's no cause for panic," she said.

"But the US credit crisis has already prompted some high street banks to raise interest rates. If indebted householders struggle to pay their debts that becomes a problem for this householder here.

"Voters have rewarded Labour for a decade of economic good times. Now, if the going gets tough, the government shouldn't be surprised if it gets the blame."

Please wait while this video loads. If it doesn't load after a few seconds you may need to have Adobe Flash installed.

Nationalising the Rock

In September 2008 the Chancellor Alistair Darling has made a dramatic announcement that Northern Rock is to be nationalised.

The chancellor said the government was forced to act after failing to attract private bids that would have given sufficient protection to taxpayers, who are now propping up the bank to the tune of £55 billion.

Last autumn, the government stepped in to save the bank, until recently the fifth largest mortgage lender in the UK.

Channel 4 News economic correspondent said the decision was one the government would have wanted to "avoid at all costs".

Chancellor Darling said: "The government has now completed it review of the two detailed proposals on the table and we have made our choice after considering all proposals.

"In the current market conditions we do not believe the two proposals deliver sufficient value for money for the taxpayer, so the government has decided to bring forward legislation to bring Northern Rock into a temporary period of public ownership.

"We have done so after full consultation with the Bank of England and the Financial Services Authority.

"Northern Rock will continue operating as a bank on a commercial basis. It will be open for business as usual tomorrow morning and thereafter.

"Importantly, savers' and depositors' money remains safe and secure. The government guarantee arrangements I announced last year remain in place and will continue to do so. Borrowers will continue to make their payments in the normal way."

The Government will take the business from its current shareholders into public ownership.

It will be run at arm's length and the former Lloyd's of London chief executive Ron Sandler has been chosen as executive chairman.

Emergency legislation will be rushed through Parliament and a government-appointed arbitration panel will decide on a fair level of compensation for Northern Rock's shareholders when the move is made, although this is likely to pave the way for a legal fight if investors are unhappy with what is offered.

Robin Ashby of Northern Rock Small Shareholders told Channel 4 News: "I am shocked and appalled. This is no answer for anybody.

"It's absolutely not the answer for the taxpayer, or the government, or the country and its reputation as a financial centre. It's no good at all for the employees, it's bad news for the Northern Rock Foundation, that relies on the profits to help charitable institutions, and it's no good news at all for shareholders who face years of litigation to get a fair compensation for the money that's been expropriated from them by the government."

"It's not quite Black Wednesday, but it is a sorry Sunday. The wrong sort of history made today by the Treasury," Channel 4 News economics editor Faisal Islam said, as £100bn of mortgage assets came onto the government's books via Northern Rock.