Mr Blair and Mr Wen were keen to stress new business deals
British PM Tony Blair and Chinese Premier Wen Jiabao have met in London to discuss, among other things, trade, climate change and press freedom. BBC diplomatic correspondent James Robbins was at Downing Street to question the leaders and here delivers his assessment of Mr Wen's visit.
By the middle of this century, China will be the world's dominant economic power.
Couple that with its rapidly growing political power and no wonder world leaders are scrambling to develop closer relations.
Tony Blair has established the pattern of an annual meeting with his counterpart, Wen Jiabao, as a crucial element in building closer ties and trying to influence aspects of China's future.
Trade between Britain and China has more than doubled over the past five years.
Among countries of the European Union, including other economic giants like France and Germany, Britain is the largest investor in China.
So both Mr Blair and Mr Wen were keen to stress the importance of new business deals.
Three were announced as part of the visit, including Air China's $800m (£425m) agreement to buy Trent 1000 engines to power its fleet of 15 Boeing 787 Dreamliner aircraft.
Pro and anti-Wen protesters greeted the premier in London
British energy giant BG Group is making its first investment in China, for deepwater exploration in the South China Sea.
The global design and engineering group Arup won an agreement to develop
a design for the new Yunnan Kunming International Airport in southern China.
It will become the country's fourth largest airport hub.
All this economic activity has profound implications for the Earth's future.
China's energy demands can seem almost limitless and Tony Blair is pressing China hard to join in global climate change initiatives.
The British government sees China overtaking the US in about 20 years as the world's largest emitter of greenhouse gases.
The greatest single source will be China's coal-fired power stations.
Britain's Foreign Office says China opens a new one, on average, every four days.
So both leaders stressed the importance of the EU-China "Near Zero Emissions Coal Initiative", designed to produce a demonstration plant by 2012, incorporating the capture of harmful carbon dioxide.
Given the breathtaking pace of the opening of lower tech, "dirty" power stations, however, Britain is now urging the acceleration of a project that is looking hopelessly inadequate as a response.
This is still the most difficult issue between China and many other leading world powers.
Today Mr Blair told us that he had raised concerns again, but paid tribute to Premier Wen's "frank and candid" private talks with him on this and a host of other divisive issues.
When I asked the Chinese premier about new limits on press freedom which seem to be closing the trade in ideas and free expression for his own people, he insisted the new controls had been misunderstood.
Reporting freedoms in China were one of the issues at the talks
"The Chinese government will ensure the freedom and rights of the foreign news media and foreign financial information agencies operating in China," he said.
"And we also hope and trust that these foreign news media and financial information institutions will also observe the Chinese law and regulations."
Mr Wen did not directly answer the point about freedom for his own citizens and for China's media.
Outside Mr Blair's office at No 10, about 100 human rights activists could be heard beyond the gates of Downing Street, protesting in Whitehall.
Banners read "Human Rights Before Trade" and "Wen Will You Free Tibet?"
There was a separate demonstration supporting Mr Wen's visit by people waving Chinese flags.
The Chinese premier was in Britain for 21 hours, according to his officials, but he packed a huge amount into less than one complete day.
Has the visit made a difference? Yes, certainly, but for good or ill depends on where people stand on the central issues.
China is opening up to an extraordinary degree, as its economy and industry expand at breathtaking speed.
Political development, however, lags far behind.
A visit I made in June reminded me powerfully how much change there has been.
But much more change is still vital if China is to handle future pressures from an exploding middle class who will surely demand a greater say in control of their own lives in years to come.
Premier Wen's host in London, Mr Blair, has no doubts.
Mr Wen's openness about China's vision of its future, he said, "augurs very, very well".
The only trouble with that - many British people no longer trust their prime minister's judgement on questions of foreign policy.