Some 50,000 government files from the past 30 years are being made public under new openness legislation.
Open up: New law now in force
The move comes as the Freedom of Information Act comes into force throughout the UK.
The records held at the National Archives are among those officials believe should be automatically published under the law.
Until now, many government papers have been kept hidden from the public for decades under the 30-Year-Rule.
Under the Freedom of Information Act, the public gains a right to ask for and see documents held by more than 100,000 public bodies. These include every organisation from central government down to local schools.
The documents being placed in the National Archives in Kew, London, include central government papers on a range of major events including the 1984-85 miners' strike. Other papers kept hidden until today include details of the Home Office's official cat.
Constitutional Affairs minister Baroness Ashton of Upholland said the Act would now have a major impact on the work of modern historians.
Until now, many historians have relied on personal interviews with figures or have had to wait 30 years to see documents relating to events.
From today, the 30-Year-Rule effectively disappears, although this does not mean all documents will be opened.
"These releases under the Freedom of Information Act provide living, breathing proof of the difference the Act is making and will continue to make over the years ahead," she said.
"Public discussion of Freedom of Information has rightly concentrated on access to contemporary information. But Freedom of Information is also about
access to the historical legacy."
Baroness Ashton said this spring would see the government release Whitehall papers dating from 1870 to 1939 on the early workings of the UK's Secret Intelligence Service. The intelligence services are exempt from the Freedom of Information Act.
Downing Street is also expected to authorise the opening of official notebooks of former Cabinet Secretaries - the civil service figure closest to the prime minister and responsible for recording exactly what happens around the cabinet table.
These papers, kept by all holders of the post, have never been seen before because ministers have considered them so sensitive. At present, historians and journalists get to see brief minutes of cabinet discussions - and then only after waiting 30 years.
The release of the papers comes as the government is already facing criticism over the Freedom of Information Act.
Critics predict that it will not prove as open as the government claims, saying its wide range of exemptions will be used to prevent the release of important papers.
A number of media organisations are applying for the secret advice from the attorney general to the prime minister on the legality of a war in Iraq.
Lord Falconer, Secretary of State for Constitutional Affairs, has defended the continued closure of that file, saying it is "only right" that governments can seek policy advice in a way that allows it to have frank discussions behind closed doors.
And writing for the BBC News website, Lord Falconer urged critics to judge the Act over the long term, predicting it will create a new culture of open government.