"Let's all become expert swimmers!" the slogan declares in triumph. "Let's grow more sunflowers!" says another. And another: "Let's breed more high-yielding fish."

©David Heather

One, rather cryptically, tells workers: "In all institutions and workplaces, let's popularise basketball," revealing a sporting passion in the Great Fatherland hitherto unknown.

They are a few of the North Korean propaganda posters that went on display in London this week, offering a rare glimpse of life - and doublethink - behind the closed borders of the most secretive country on Earth.

The exhibition features 400 hand-painted posters dating from the peak of the Great Leader Kim Il-sung's power in the 1950s to the present regime led by his son, Kim Jong-il.

But unlike their Chinese and Russian variants, which depict a long-gone period of history, many of the posters are still used to promote the policies of the "hermit kingdom".

Artists continue to produce them and, according to the few foreigners who get into the country, they can still be seen in schools and factories.

They have been brought to the UK thanks to the artful diplomacy of David Heather, a British collector.

"The fact there are posters dating from the 1950s right up to 2007 shows the thought processes of the country," said Mr Heather, who developed an interest in North Korean culture after meeting an artist from the country in Zimbabwe four years ago.

"You can see from the other side how the people are being informed of what is happening as the Government sees it. And it will hopefully enable people here to understand a little bit more about why the Koreans are in this position."

There are posters penetrating every aspect of North Korean life, with slogans explaining how it should be lived: "Let's create a social impetus for enjoying wearing our national dress".

Colour scenes of the workers' paradise encourage farmers to boost production in a nation beset by famine and corruption. The Korean War - or the Great Fatherland Liberation War, as it is known in the North - is also a common theme: "Let's not forget the blood-drenched hatred!"

No enemy is hated as much as America. Clenched fists smash US soldiers. The slogans scream: "Let's take revenge a thousand times on the US imperialist wolves!"

But the posters can be quite tongue-in-cheek, Mr Heather said. Some invert the country's place on President Bush's "Axis of Evil" as a badge of pride: "The world turns with Korea as its axis." Another claims: "Our missile programme is a guarantee for world peace and security."

The collection, showing at Foyles Gallery, Charing Cross, until May 7, is the first of its kind to be exhibited in Britain. It is the latest cultural attempt to prise open the police state.

The performance of the New York Philharmonic in Pyongyang in February suggested a shift in diplomatic relations with its sworn enemy. The same week, Eric Clapton became the first Western rock star to be invited to perform in North Korea.

Recently the British opera singer Susannah Clark won permission from Pyongyang to take the state orchestra out of the country for the first time to tour the UK. She will bring the 120 musicians to perform in London and Middlesbrough in September.

Ms Clark, who is seeking sponsors, said: "These projects will introduce North Korean culture to people. All these events represent a great step forward with regard to coming to understand each other's cultures."

Culture vultures will then be able to form their own view of the mysterious country that declares: "There can be no world without Korea."

Newspeak in action

- Nobody in the world can defeat us!

- Let's expand goat rearing and create more grassland in accordance with the party!

- Just as it began, the revolution advances and is victorious, through the barrel of a gun

- Let's be invincible in every fight

- Let's achieve even more supremacy

- Let's make wearing the beautiful and elegant Korean dress a lifestyle

- The reunified fatherland is at the tip of our bayonets