1996 - An Undiscovered Source
A substantial part of the November 1996 budget was leaked to the Daily Mirror newspaper. The paper obtained 36 documents, mainly press releases which were to be distributed after the Chancellor had finished speaking.
The editor of the paper, Piers Morgan, returned them to the Government without publishing them, saying that he had "a public duty to return such sensitive documents". But Tony Blair, then Opposition leader, was able to take advantage of being extremely well-prepared when he rose to deliver his Budget response after the Chancellor sat down.
John Major, the Prime Minister at the time ordered a public inquiry by the Metropolitan Police Sevice into how the documents found their way into the hands of a newspaper editor. No police action followed the inquiry.
1969 - Sir Gerald Nabarro
In the lead-up to the Budget in 1969, the Conservative backbench MP Sir Gerald Nabarro's repeated claims that the car tax (vehicle excise duty) was about to be raised in the budget (from £25 to £35 per annum) prompted the Prime Minister, Harold Wilson, to set up a Select Committee to investigate a possible breach of budget secrecy.
Despite Sir Gerald's claims that civil servants and members of the public alike had informed him of the impending rise, the committee found no evidence of a leak. Even so the publicity may have prevented car tax being raised by Chancellor Roy Jenkins that year.
Sir Gerald himself cut a colourful figure and was celebrated not least for his ownership of a number of classic cars with consecutive 'NAB' number plates.
1947 - Hugh Dalton
Following the 1947 Budget, Hugh Dalton resigned as Chancellor of the Exchequer after it was discovered that he had divulged his plans to a lobby journalist from The Star on the eve of his statement. The news appeared in the paper on the day of the Budget and Dalton was left with no alternative but to apologise to the House and resign.
1936 - Jimmy Thomas
In 1936 Jimmy Thomas, a Cabinet minister, was found guilty by a Tribunal of Inquiry of leaking budget proposals to Sir Alfred Butt, Conservative Member of Parliament for Balham and Tooting. It was also believed that Mr Thomas had divulged budget secrets to a friend and business associate, Alfred 'Cosher' Bates, for personal gain.
Mr Thomas resigned from Baldwin's government, and then, shortly afterwards, resigned his Commons seat.