In among the demands laid down by Japan to UK in the wake of the Brexit vote is one that goes straight to the heart of Canary Wharf .

It comes in an extraordinary document that Japan sent as a “message” to the UK, warning that the presence of the country’s banking and manufacturing industry in the country is imperilled by Brexit and a poor deal with the EU over free market access could see a large-scale withdrawal. Some Japanese banks in the City, it is feared, may move their headquarters into continental Europe.

Honda, Nissan and Toyota have major bases in this country along with Nomura and Daiwa banks in the City.

One of the 18 demands that Japan makes, however, concerns an organisaion it doesn’t want to see move. The European Medicines Agency is based in Canary Wharf and is used by Japanese pharma for certification.

Japan's Prime Minister Shinzo Abe attends a news conference during the G20 Summit in Hangzhou, Zhejiang Province, China

The document warns: “Many Japanese pharmaceutical companies are operating in London, due to the EMA’s location. If the EMA were to transfer to other Member States, the appeal of London as an environment for the development of pharmaceuticals would be lost, which could possibly lead to a shift in the flow of R&D funds and personnel to Continental Europe. This could force Japanese companies to reconsider their business activities.”

Read more EU drug agency could leave Canary Wharf for Dublin

The future of the EMA is yet to be decided but a number of countries, notably Ireland, are angling to become the agency’s new home. It is unlikely that any EU operation will remain in the UK for longer than is necessary once Britain cuts ties with Brussels.

A UK Government spokesman said: “We recognise the value of Japanese investment in the UK – including a recent record £24billion investment by Japan’s SoftBank in ARM Holdings.

“With a strong economy, flexible labour market, highly skilled workforce and low taxation, the UK remains an attractive location for foreign investment.”