In the mid 1980s London Greenpeace - a group unconnected to Greenpeace - began campaigning against McDonald's, with postman David Morris and gardener Helen Steel handing out a leaflet critical of the American hamburger chain.

The firm decided to sue Mr Morris, 50, and Ms Steel, 39, for libel, triggering what became a mammoth court case that started in 1994 and went on for three years.

The relatively penniless activists represented themselves against the corporation's lawyers at the high court. At the time of the McLibel hearing Ms Steel's income was £65 a week from part time bar work and Mr Morris was on income support. In contrast there were some 11,800 McDonald's restaurants in 53 countries with total sales of more than £10bn.

What was the leaflet about?

Entitled "What's wrong with McDonald's: everything they don't want you to know", the leaflet accused the company of paying low wages, of cruelty to animals used in its products and dozens of other malpractices.

The high court judge found that some of the leaflet's claims - that the company was to blame for starvation in developing countries, for example, and that its food caused cancer - were untrue.

But he also found McDonald's "culpably responsible" for animal cruelty and that it exploited children through its advertising.

The judge also found that McDonald's paid low wages, but that the company had been libelled because other aspects of the material were defamatory.

The pair were ordered to pay £60,000 in damages, later reduced to £40,000 on appeal in 1999. Both refused to pay.

The case was thought to have cost the fast food giant £10m and has been described as the biggest corporate PR disaster in history.

How did the libel trial break a legal record?

At 313 days the case was the longest civil or criminal case in English legal history.

The length added to the sense that the two sides were massively mismatched. Mr Morris and Ms Steel at times cut exhausted figures as they tackled McDonald's lawyers and worked through tens of thousands of pages of legal documents.

So why did they want a second case at the European court?

They were aggrieved that English libel law denied defendants legal aid, creating a "David versus Goliath" situation that prevented campaigners from taking on big corporations. And of course they did not want anyone else to have to go through a similar ordeal.

Did they represent themselves again?

The pair were granted legal aid to challenge the government in the European court of human rights. Their lawyer said they were "untrained and exhausted individuals who [had been] pushed to their physical and mental limits".

He also questioned whether it was right that the onus in English libel law should be on the defendants to prove all of their statements were correct, rather than on those seeking damages to prove they were inaccurate, as is the case in some other countries.

What was today's ruling?

Today the 15-year saga continued in the European court of human rights in Strasbourg with the so-called McLibel Two winning a separate case they had brought against the UK government.

The court upheld their case that defendants in libel cases should be given legal aid. The pair had argued that their libel hearing had been "patently unfair" because they could not afford lawyers and had been forced to represent themselves.

What does today's ruling mean?

The judges upheld the McLibel Two's contention that lack of legal aid had breached their rights to a fair trial and their freedom of expression, both of which are enshrined in the European convention on human rights.

The ruling will now be scrutinised by lawyers, but the British government may be forced to change the libel laws. A Department for Constitutional Affairs spokesperson said: "We are studying the judgement very carefully."

The libel laws have already been changed since 1997, meaning defendants can sometimes qualify for legal aid under "special measures".

Is McDonald's still being targeted by campaigners?

Last year marked 30 years since McDonald's arrived in the UK, but celebrations were low key. Pre-tax profits of the British part of the company collapsed by almost three-quarters from £83.8m in 2003 to £23.5m in 2004.

Health campaigners said this showed British consumers were embracing healthier lifestyles. McDonald's responded by promoting a new range of foods it says are healthier and will boost profits once more.

The firm is still targeted by campaigners and was recently the subject of a hit documentary, Supersize Me, by the US filmmaker Morgan Spurlock, who lived exclusively on McDonald's products for a month. His physical, mental and emotional condition deteriorated markedly during the month.