by Nick Higham BBC media correspondent

The row between the UK Government and the BBC over an Iraq dossier is not the first time there have been tensions between politicians and the broadcaster.

In July 1932 the BBC's chairman and director general were summoned to a meeting with a government minister and told to cancel a proposed broadcast by a former World War I German U-boat captain, Ernst Hashagen.

As part of its efforts to get the BBC to comply, the government threatened to cancel the royal opening of the newly-constructed Broadcasting House.

Tony Blair's communications director, Alastair Campbell, hit back at the BBC

The Beeb caved in, but the chairman wrote a letter to the minister pointing out how the intervention ("incredible if it had not happened") had damaged the BBC's credibility, reputation for independence and international prestige.

In the years since there have been scores of run-ins between the BBC and the government of the day. The latest, Gilligangate, is among the more serious, but it is not unique.

For the most part these episodes follow a predictable pattern.

Virtually always the BBC's response reflects its determination to protect its independence - which for 70 years has been an essential element of its reputation for trustworthiness.

Often the spats occur when Britain is at war, or when the subject is terrorism.

Sometimes threats are uttered, usually in private. Very occasionally the government exercises its power to humble the unruly corporation.

In the 1970s and 80s Northern Ireland was a constant source of tension.

One Northern Ireland secretary, Roy Mason, bluntly threatened not to increase the licence fee if the BBC didn't stop giving aid and comfort to terrorists.

Comply

The worst moment came with the 1985 row over the Real Lives programme in which Martin McGuinness was interviewed.

The BBC's run-ins with the Conservative government of the 1980s had real consequences

The government called on the BBC not to broadcast it.

With the director-general, Alasdair Milne, on holiday the BBC governors watched it and decided to comply.

In the uproar that followed BBC journalists staged a day-long strike, supported by those at ITN and Independent Radio News, and the programme was eventually shown with only minor amendments.

Three years earlier Milne and the then-chairman, George Howard, had been "roasted alive" by a meeting of backbench Conservative MPs during the Falklands War.

The MPs were furious at what they saw as the BBC's unpatriotic coverage and in particular by a Panorama programme which gave a voice to those opposed to the war.

News and current affairs producers were subsequently reminded in an internal memo that the BBC's reporting had to be "sensitive to the emotional sensibilities of the public".

The BBC's run-ins with the Conservative Government of the 1980s had real consequences.

The ban on broadcast interviews with supporters of terrorism was a direct result of episodes like Real Lives.

When opportunity arose a new chairman, Duke Hussey, was appointed to "sort out" the BBC: one of the first things he did was fire Milne.

But things might have been worse for the Beeb.

A Thames Television programme, Death on the Rock, about the SAS killings of three IRA terrorists in Gibraltar, was blamed for the government's decision to auction ITV franchises to the highest bidder - a decision which cost Thames its licence.