Revealed: The secret plans Northern Rock made to pull the plug

Accounts would have been frozen, cash machines switched off, every branch closed and online services axed for the closure on what was dubbed 'D-Day'.

The measures show how the stricken bank had made intricate plans if it needed to hit the panic button.

Northern Rock revelation: Customers queued up for their savings but would have found branches closed if secret plans went ahead.

They also highlight just how anxious the board was only weeks before the bank was nationalised in February.

Investors, many of whom have been with the bank for decades, would have been sent cheques within 14 days.

All 76 branches would have closed immediately as bosses feared leaving them open after the closure would have put staff at risk.

Angry and frantic customers would not even have been able to call their branches as all calls would have been directed to head office in Newcastle.

The explosive contingency plan would not have hit the Rock's 800,000 mortgage customers 'for the foreseeable future'.

Rapid Plan was drawn up after last September's extraordinary scenes when customers queued to withdraw their money.

Only a tiny number of insiders were privy to the information. The run by investors was prompted by revelations the Rock had borrowed money from the Bank of England to head off collapse.

In November, there was a second run. Fears grew at the Treasury about the precarious state of the bank whose collapse in a Labour heartland would have been a political disaster.

In the end, Chancellor Alistair Darling had to guarantee every penny of savings to stem the crisis.

But the draft documents reveal how close the Rock was to a virtual wipe-out.

The Daily Mail first learned of the bank's secret plans in January but, after a late night call from Mr Darling, was begged not to publish.

In the detailed plans, mass closures would have started on a Friday afternoon when 500 branch staff would be told to stay until 5pm for a 'business update' meeting.

In reality, insiders, known as 'Briefers' would arrive at 4.45pm to break the news of the closure.

Staff would have been told to go home and await further news while still receiving salaries and expenses.

At 6.30pm, when most of the City had left for the weekend, the bank would have made its extraordinary announcement.

Unions would not have been informed until the last moment on Friday.

The documents are very detailed, suggesting the bank was taking the threat of collapse seriously.

Letters had been drafted to be sent to branch staff explaining the decision and giving a helpline number.

The plan also outlined the 'activity' that would take place behind the scenes before the announcement was made.

'D-Day minus 1 and 2' includes a forensic level of preparation, such as photocopying 1,000 Q&A sheets. Earlier that week, an e-mail would have been sent to branches telling them to update all accounts by the close of business on Friday for end-of-year accounting.

But the real intention was to ensure everything was ready for the final-balance cheques for customers.

Since nationalisation, many of the Rock's 6,000 workers have faced an uncertain future.

Last night a Treasury spokesman said: 'Northern Rock sensibly developed robust contingency plans to ensure it could return depositors' money swiftly. '

The Government continues to guarantee all deposits. Savers' money remains absolutely safe.'