As the sun set over London on the eve of the royal wedding, die-hard fans from around the world settled down for a chilly night outside, determined to get front-row seats for the historic occasion.

Thousands of campers pitched up on Thursday, transforming The Mall, the road leading to Buckingham Palace, into a multicoloured sea of flags and outlandish headgear as enthusiasts vied for the best spot to cheer the newlyweds.

Some of them were lucky enough to catch a glimpse of Prince William when he made an impromptu evening visit to shake hands with well-wishers, before retiring to spend his last night as a single man with his family.

William was heard telling his fans: "All I've got to do is get the lines right".

A huge contingent of Britons was joined by many nationalities including Americans and Australians, who set up encampments with their countrymen to add an international flavour to William's marriage to Kate Middleton.

"It's the final countdown," said Cindy Bernard, from Louisiana in the United States, wearing a bright red, wide-brimmed sunhat with a US flag fluttering from the top.

"We are getting more and more excited."

Union Jack flags fluttered in the breeze along the broad, tree-lined road, which William and Kate will travel down after becoming man and wife, with enthusiasts sporting wacky outfits from plastic crowns to tuxedos.

As temperatures dropped and the sky clouded over, spirits remained high among the excited royalists spending the night in the international tent city.

Bernard, 53, and her friends had turned their campsite into a shrine to William and Kate, with homemade posters saying ‘Best wishes from America’ and ‘True love really does exist’.

Despite having a hotel only several hundred metres (yards) away, they decided camping out was their only option with hundreds of thousands expected to pack the streets.

"We wanted to get front-row seats," said Bernard. "We'll be cheering and screaming."

Less than 50 metres (55 yards) from the gates of Buckingham Palace, a group of Australians sporting hats with corks dangling from them set up base, plastering the metal security barriers with dozens of their country's flags.

"We didn't want to miss out on it," said Gimyana Malek, a personal assistant working in the financial sector from Sydney, who had arrived at 9:00 am (0800 GMT) to get the prime spot.

"We could choose to watch it on TV but it is such a nice experience to be in the front row."

While most of the campers began arriving early on Thursday to set up camp on The Mall, some took the race for a place even more seriously.

Margaret Tinsley was the first to arrive, pitching her tent at midday on Wednesday, a feat she also achieved for Prince Andrew and Sarah Ferguson's wedding in 1986 and for the Queen Mother's lying-in-state in 2002.

"We wanted to be first on The Mall, and we were," said the retired 69-year-old, from the New Forest in southern England.

"When we got here yesterday, there was no one else, just us, we were the first this time and we were first last time."

Campers trying to get a good night's sleep were awakened early on Friday as fireworks lit up London's night sky.

Predictions of wedding day rain did little to dampen spirits, with royal enthusiasts choosing to stock up on umbrellas from passing street sellers rather than retreat inside.

"We are not worried about the rain tomorrow, we'll be here until the bitter end," said Pru Marriott, a university lecturer in her 40s from Cardiff, Wales.

She was dressed as a daffodil, the national flower of Wales in honour of the royals' Welsh connections.

Prince Charles, William's father, is officially called the Prince of Wales, and William lives on the Welsh island of Anglesey.

Age was no barrier to getting a good view of the biggest royal wedding for 30 years Gwen Woolley, 73, from the village of Rocester in central England, planned to sleep out with only a sleeping bag and a blanket.

"I'm not at all worried about camping out overnight," she said. "We'll be cosy when we've got the sleeping bags on."