With the end of the Shanghai Expo on Sunday, the man behind Britain's award-winning involvement in the Expo has praised the city's organization of it and said that it has put Shanghai firmly into the league of world-class cities.

Sir Andrew Kahn, the chief executive of UK Trade and Investment (UKTI), told Xinhua: "I think Shanghai has gained an enormous amount from the expo.

"Shanghai is, anyway, an enormously dynamic, rapidly growing, self-confident world city. But it has changed from being an aspirant world city to being a real world city. The world has come to Shanghai and, the expo has made Shanghai more cosmopolitan."

Kahn was impressed by the organization, the investment and the new infrastructure in Shanghai. "There is a lot of new infrastructure. Shanghai's infrastructure is now world class," he said, adding: "The expo has given a new confidence to Shanghai, and there is a spring in the step to the city. So I think it's had a hugely beneficial success for Shanghai, particularly commercially."

Kahn said that holding an expo was a challenge, and one that some cities rose to better than others. The Shanghai Expo had been a great success, he said. "I think Shanghai has shown how to do it bigger and better than anyone. I would congratulate the Shanghai city authorities. They have run a very good expo. They have managed the organization in a very practical, very effective way."

Historically expos can change a city for much the better, or much the worse, said Kahn, citing the positive example of London in 1851, which held world's first expo called the Great Exhibition. "It consolidated London's position as the number one city in the world," said Kahn.

However, some expos disappear without leaving any impact, and others are too costly and loss-making for the hosts, said Kahn, citing the unfortunate experience of Montreal as an example of the latter.

Kahn said the British Shanghai Expo pavilion had been his most pleasurable project in his five years heading UKTI, and said that involvement in the expo had been a necessity.

"Why did we get involved?" he said, "This was going to be a very easy decision to take. This was going to be the largest expo ever; it was very important for China, and China is very important for us and we want to be part of its success."

Kahn said, "the question we asked was what sort of pavilion did we want. What sort of image of Britain did we want to offer to the Chinese people? Would it be the traditional image of Britain as a heritage country with lots of manufacturing and lots of business? This is what you find at most expos, most of the time. The difference was we wanted something different and new."

He said that it was decided to go for the "most risky, exciting and innovative of the designs" submitted, Thomas Heatherwick's seed pavilion.

About eight million people visited Heatherwick's design, which Kahn described as "the most creative, the most unusual, the most extraordinary pavilion in the expo."

Kahn also looked forward to a positive legacy in Anglo-Sino relations, "I hope that the legacy of the British pavilion will be that the Chinese people see Britain in a new light. The Chinese view of Britain was that it was very reliable, very traditional, a bit of a backward-looking country. That's not a correct perception. We wanted to change that perception to one of Britain as a cutting- edge, forward looking, creative country. And I think that is the shift that has happened."

Heatherwick's design for the British pavilion was given the gold award for the best pavilion by Chinese Premier Wen Jiabao on Sunday, and had previously won the Royal Institute of British Architects Lubetkin Prize for outstanding work in international architecture.