The Queen described President Xi Jinping's State visit to Britain as a "defining moment" for the future of Sino-UK relations last night (Tuesday) as the Chinese leader spoke of the "everlasting friendship" between the two countries.
Barely two years after full diplomatic relations were restored, Mr Xi insisted his four-day visit would lift the bilateral relationship to "a new height".
The first day of his high-profile stay in the UK, during which pounds 30 billion of trade deals are expected to be agreed, ended with a State banquet that reflected both the pomp and the pressure of a day in which tension was never far from the surface.
The dinner table at Buckingham Palace glistened with gold but the deliberate absence of the Prince of Wales from the set-piece event was a constant reminder that China's record on human rights remains a barrier in its relations with the West.
The Queen described the first State visit by a Chinese premier for 10 years as "a milestone in the unprecedented year of co-operation and friendship between the United Kingdom and China" as David Cameron and George Osborne pursue a policy of making Britain China's most important European trading partner. In turn, Mr Xi urged his audience at Buckingham Palace to "seize the opportunity" to build a new era of prosperity.
It was a day when ceremony and small talk provided a safety net against the constant threat of offence being caused or taken.
It came to the fore when Mr Xi was invited to address members of the Lords and the Commons in Parliament, a moment which the Speaker, John Bercow, exploited for his own ends. David Cameron would already have feared the worst after Mr Bercow had made a pointed reference during a parliamentary debate earlier in the day to China and India, saying: "Of course the Indian prime minister is the representative of a great democracy." It is only two years since China allowed David Cameron in from the cold after a 14-month diplomatic deep freeze imposed as punishment for meeting the Dalai Lama, leader of the disputed territory of Tibet, against Beijing's wishes.
So Mr Bercow's reference to the recent visit of Aung San Suu Kyi, "international symbol of the innate human right of freedom", would have been regarded by Mr Cameron as unhelpful, to say the last.
Not that Mr Bercow was alone in ratcheting up the pressure. The Prince of Wales, whose office has failed to come up with a convincing reason for his decision to miss last night's State banquet, spent much of the day seemingly trying to avoid being seen smiling in the presence of the Queen's guests.
As a close friend of the Dalai Lama, the Prince, who once described Chinese leaders as "appalling old waxworks", has long had an uneasy relationship with China.
When he welcomed the Chinese leader to Britain at the Mandarin Oriental Hotel in London, Mr Xi was smiling warmly in an official picture, while the Prince looked rather glum. No reporters were allowed to witness the meeting.
Then it was on to Horse Guards, where President Xi was invited to inspect an honour guard and the Queen introduced him to Mr Cameron, Theresa May, the Home Secretary, Alan Yarrow, the Lord Mayor of the City of London, Sir Bernard Hogan-Howe, the Metropolitan Police Commissioner, and the heads of the armed forces.
Later, when the Queen and the Duke of Edinburgh posed with President Xi and his wife on their way in to Buckingham Palace, the Prince of Wales stalked up the steps in the background, ignoring photographers and TV cameras.
They had travelled to Buckingham Palace in a carriage procession, where ceremony once more masked anxiety as Free Tibet protesters booed from the sidelines. Pro-China supporters countered them by playing the Chinese national anthem.
After a private lunch, the Queen, the Duke of Edinburgh, Mr Xi and his wife Madame Peng Liyuan viewed an exhibition of items from the Royal Collection in the Palace's Picture Gallery.
The Duke, who famously commented during a tour of China in 1986 that British visitors would end up "slitty eyed" if they stayed too long, was on this occasion a welcome provider of light relief.
He gestured to an aquatint portrait of Emperor Qianlong from 1795 and told Mr Xi: "There's one of your predecessors!" As the Queen spotted a photo of herself in China in 1986, she remarked: "That's me".
Mr Xi was quickly off to Parliament, where he used his speech in the Royal Gallery to make his own subtly nationalistic comments: he may have been in "the mother of Parliaments", he said, but it was China, 4,000 years ago, that first started putting the public at the centre of politics.
On safer ground, he described how 24 Chinese naval cadets took part in the Normandy landings and received personal thanks from Winston Churchill for their gallantry.
Mr Xi praised MPs and peers for their work to improve ties between the countries and said: "I hope that you will build a bridge of understanding and co-operation so as to help create an even brighter and more promising future of our bilateral ties." He managed to fit in private meetings with Jeremy Corbyn, the Prince of Wales and the Duke of Cambridge, before changing for the white tie banquet.
As Prince William left his personal meeting with Mr Xi, he came across the Labour leader who was sitting on an ornate low pink sofa waiting in the Bow
Room for his turn. The pair shook hands and chatted animatedly for
several minutes.
Opponents of Mr Osborne's trade policy have warned that Britain will "rue the day" it forged deeper ties with China and accused the Government of acting like a "panting puppy".
There will, no doubt, be plenty more tense moments ahead during the visit, but the State banquet provided a welcome chance to put differences aside, and toast, what the Queen described as the "warm and longstanding friendship" between the two countries.