By Dominic Casciani
BBC News community affairs
It was a curious battle of flags, complete with a British tolerance for the other point of view.
Gagged in China - being heard in London: Tibet campaigners
President Hu Jintao of China was to be accorded the finest of welcomes to the UK: An official hello from the Queen, a carriage ride up the Mall, flanked by the Household Cavalry, and a nice cup of tea (China, we suppose) before getting down to business.
Oh, and then there were the protesters.
The last time the Chinese came on a state visit, in 1999, the police seized banners and blocked demonstrators from seeing Mr Hu's predecessor, Jiang Zemin.
This time, the demonstrators were to be allowed to have their say and a few hundred turned out with more than enough banners (and symbolic gags over their mouths) for most of the passers-by in St James's Park.
Free Tibet campaign
By far the biggest - and loudest - contingent outside Buckingham Palace were the Tibet campaigners, people who believe that China has no role in the territory invaded by the Chinese Red Army half a century ago.
Many wore bandannas declaring "Free Tibet"; almost all carried the national flag (an arrestable offence in China) while others wore elements of national dress as a symbol of the importance of their culture.
Chonpal Tsering and Sonam Dugdak were carrying posters in Chinese script appealing for an independent Tibet. In 1989 Sonam had his placard confiscated by police officers.
"Hu Jintao cannot continue to ignore Tibet," said Chonpal. "This has gone on for 50 years and it is time for meaningful negotiations and dialogue. We have to find a solution and the Dalai Lama [Tibet's exiled spiritual leader] has been extremely generous to China - but we need Hu to demonstrate wisdom and start talking."
"The police seem to have learned from back then," said Sonam. "That time they were heavy-handed. I think looking at the way they are handling things today, they know they were wrong and are allowing us to get out voice heard."
Then there were the Falun Gong spiritualists. The rise of Falun Gong as a mass movement has been one of the most curious stories of modern China. It's a combination of spiritual meditation and exercise - and Beijing sees it as a threat to its power.
Theirs were the biggest banners, written in Chinese and English, calling for the release of followers arrested for their beliefs. While the Tibetans noisily chanted, the Falun Gong followers mostly stood or sat in silent contemplation.
Falun Gong: Protest through meditation
Michael Lee, one of the organisers of the Falun Gong contingent, said they were people seeking "compassion and forbearance".
"China has no human rights - how can it when our members are imprisoned and tortured for simply seeking spiritual wellbeing," said Mr Lee.
"The Chinese Communist Party is persecuting our followers yet all we want to do is talk. We do not mind that Mr Hu is welcomed to Britain by the Queen - but we would like to be able to tell him ourselves what we stand for as we are not a political movement.
"We cannot speak to him so we will be staging a vigil over the coming days outside Buckingham Palace."
Police: Relaxed presence
Further down the Mall there was a lone protester against the 2008 Beijing Olympics and a sprinkling of people speaking up for Taiwan.
Next to them was a small compliment of Uyghurs. These are people from the territory of East Turkistan. They don't speak Chinese, write using Arabic script and are predominantly Muslim.
Ilyar Pehridin, a former refugee and member of the British Uyghur Association, said that their cause was the forgotten one amidst the vast swathe of complaints against China. Their culture is being eroded, he said, amid immigration policies designed to fragment the Uyghar identity and suppress its language. Since 9/11, he claimed, the Chinese government had used general fear of Islamist extremism to crush peaceful dissent by Muslim people in the territory.
"Our people are completely oppressed and cannot challenge China's rule," he said.
"If we even raise our flag, it is an offence. I am very surprised that the British state would give such a reception to Mr Hu when we all know the abuses he is responsible for. But today I stand here as a proud British citizen, exercising my right to protest."
But those angry with China were not alone. Across the road, separated by police officers and the ceremonial Household Guard, were roughly an equal number of Mr Hu's supporters. They eagerly held British and Chinese flags, mirroring those flying from the Mall's ceremonial flagpoles.
Any suggestion that the Chinese Embassy had put them up to it was media cynicism, they insisted.
Students: Welcoming Mr Hu
"I'm here because I want to welcome our chairman," said John Man, a businessman. "This is an important trip and we need to see it go well."
What did he think of those across the road?
"They're crazy and mad," he said. "We have one China and these people just want to do their own thing."
Imperial College students Tony Wei and Guanhua Liu said they were all for greater ties between China and the UK, particularly because of China's growing economic power.
"Human rights in China are not that bad, these people [the Tibet campaigners] are out of order," said Tony. "I'm proud of my country and what it has achieved."
How did he feel that he was free to say this in Britain - but those across the way were not free to say what they wanted in China?
"Whether that is good or bad is difficult to say," he said after some thought.
And it was to these supporters that Mr Hu turned his face as he passed along the Mall with the Queen sitting by his side. Hand raised in recognition, the president enthusiastically smiled and waved as they cheered his arrival.
The Tibet campaigners, joined by healthy-lunged British students, shouted as loudly as they could. But there was not a flicker of recognition on the president's face.
The Queen did, however, see them. She was sitting on the right hand side of her coach, closest to the demonstration. As they passed, she scrutinised the banners with an indecipherable composure.
"If the conversation gets dull during lunch, perhaps she'll ask him what he thought of our flags," smiled one Tibet campaigner.