China has begun its first freight train service to London from Yiwu, a famed wholesale market town in the eastern province of Zhejiang, the Xinhua news agency reported.

The train will travel for 18 days over more than 7,500 miles (12,000 km) to reach Britain from China, Xinhua said. It will pass through Kazakhstan, Russia, Belarus, Poland, Germany, Belgium and France before arriving in London.

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Former British Prime Minister David Cameron raised some eyebrows with allies by pitching Britain as the pre-eminent gateway to the West for investment from China and proposing to make London the main international trading centre for offshore yuan.

Prime Minister Theresa May has said the relationship with China remains "golden" as she seeks to bring in billions of dollars in Chinese investment as Britain prepares to leave the European Union.