![(FILES) In this file photo taken on July 24, 2019 Britain's Prime Minister Boris Johnson (CL) shakes hands with Cabinet Secretary Mark Sedwill (CR), Head of the Civil Service, as he is clapped into 10 Downing Street in London on July 24, 2019 by Mark Spencer (L) and Johnson's special advisor Dominic Cummings (R) among other staff after he accepted the invitation from Queen Elizabeth II to become Prime Minister and form a new government. Mark Sedwill has announced on June 28, 2020 he will stand down from his role as Cabinet Secretary, National Security Adviser and head of the Civil Service in September 2020. / AFP / POOL / Stefan Rousseau](https://thenational-the-national-prod.cdn.arcpublishing.com/resizer/v2/63TG6D6G7LU6DFLVETNQSYG4YU.jpg?smart=true&auth=0311c67cf70637b0cdd552c5355c8d0fd59e231721775e3288371213a9b1bdbd&width=400&height=225)
Britain's Prime Minister Boris Johnson, left, shakes hands with national security adviser Mark Sedwill. AFP
Britain's Prime Minister Boris Johnson, left, shakes hands with national security adviser Mark Sedwill. AFP
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