A major review of Britain's foreign policy has been triggered by Prime Minister Boris Johnson to take account of post-Brexit realities from January 1, 2021, when the government hopes to sign a free trade agreement with India, among other non-EU countries.

"As the world changes we must move with it," Johnson said, while announcing the review as part of his bid to forge a 'Global Britain'. Foreign policy experts, inside and outside the government, are to be consulted to constructively challenge traditional assumptions.

The review, billed as the largest such exercise since the Cold War, is expected to "cover all aspects of the UK's place in the world", officials said. It will include the diplomatic service, besides approach to defence, security and international development.

One of the UK's largest diplomatic networks is based in India.

Johnson said: "I am determined to lead a Government that delivers for our people - both at home and abroad. The UK's institutions, expertise, leadership and values are renowned around the world".

"But we cannot rest on our laurels. We must do more to adapt. We will be judged by how we respond to the opportunities ahead".

The Johnson government believes that Brexit presents new opportunities to define and strengthen Britain's place in the world at a time when the global landscape is changing dramatically.