"It's a momentous day, it's a watershed moment in the history of South Africa," said Stanley Jacobs as he looked upon the hundreds of fellow countrymen lining up to vote in London.

South Africans go the polls for the country's general election on May 29, but the South African High Commission on London's iconic Trafalgar Square is open this Saturday and Sunday to allow the UK's 25,000 strong expat community to cast votes.

Voting began at 7.00am (0600 GMT) and by 9.00am hundreds of voters snaked through the streets around the London landmark, turning it into a sea of South African flags.

Many in the 90-minute queue wore South Africa rugby shirts, headwear and scarves while others draped themselves in their national flag as music blared out, giving the occasion a carnival feel.

Jacobs, originally from Eastern Cape, is the chairperson for South Africa's "Patriotic Alliance" party in the UK and Europe, and hopes the upcoming election will bring about change.

"This is the biggest crowd I've ever seen" at the embassy, he said, having voted many times in London since moving to the British capital 23 years ago.

"It's about change, and it's about changing the lives of those who have been left behind for the past 30 years," he added, saying it was time to vote out the ruling African National Congress (ANC).

"I've been ANC since I grew up because of the liberation struggle," he explained.

"But the ANC has failed too many communities, the community I am from -- I'm from the coloured community -- in particular.

"They've failed in every aspect of good governance. People have become disillusioned, disheartened. Poverty has become worse under this government."

He was not the only one hoping for change among the crowd, with visible support for several different parties on display.

Many were wearing stickers of the main opposition "Democratic Alliance" (DA) party, while one group wore red berets declaring support for the "Economic Freedom Fighters" (EFF) and its leader Julius Malema.

  'Turmoil'  

Despite the rival factions, the mood was of celebration and patriotic pride.

"It was actually quite exciting, the environment, having South Africans gather for such a worthy cause. It's been great," said chartered accountant Sise, 28, who was hoping for a coalition government.

"I'm looking at the turmoil that the country has been going under for the past couple of years, maladministration the vast practices of corruption," he explained.

The performance of the ANC was a common theme among voters.

"I'm hoping that the ANC does not get the majority," said 52-year-old environmental scientist Ilse Steyl, who has lived in Southampton, southern England, for 24 years and originally hails from Free State.

"The country is falling to bits. I can't live there, I'd rather live there but the crime, the infrastructure is completely falling apart," she said.

"You seem to be in constant fear of your life."

Sam Van Noordwyk, 41, got up at 4.00am to travel from Bedford, north of London, and cast her vote for DA.

"South Africa is a beautiful country and the way it has gone is a shame," she told AFP, adding she was hopeful of change.

"If you're not optimistic what else do you have, why bother standing here and voting?"

But the ANC weren't without support, with Lawrence Ndou and his wife Mofaladi Ndou, dressed in colourful traditional dress that contrasted with London's slate grey skies, casting their vote for the government.

"We got up around 5.00am, my husband could not even sleep" due to the excitement, Mofaladi Ndou told AFP.

She was voting ANC because she was worried that new governments "tend to feed their pockets before working for the nation", but was ultimately hoping for a coalition government.

"I still want ANC to be there," she added.