European Commission President Jean-Claude Juncker was cautious when asked about Theresa May, who will be Britain's first woman prime minister since Margaret Thatcher.

Before the referendum, May had campaigned for Britain to remain in the EU, albeit in a low-key fashion. Since the vote, she has repeatedly said that "Brexit means Brexit" and her backers say she is determined to make the exit a success.

Supporters say she has steely determination, pays attention to detail and focuses on getting on with the job at hand. She has also been described by a Conservative Party grandee, Ken Clarke, as a "bloody difficult woman".

The EU has found itself in a vulnerable spot after the shock British vote to leave what is still a 28-nation bloc and cast a long shadow over its future.