David Frost is a controversial appointment for National Security Adviser

One of Boris Johnson’s closest allies, David Frost – who has been negotiating the terms of the UK’s future relationship with the EU – is to become National Security Adviser, succeeding Sir Mark Sedwill, who is standing down both as cabinet secretary and NSA.

This is an unusual and controversial appointment because Frost is a political appointment, a special adviser, in his current role – and will continue as a political adviser rather than becoming a member of the civil service.

There will be a formal process to find a new cabinet secretary.

Frost is close to Dominic Cummings, and is routinely referred to as ‘Frosty’ in Johnson’s circle. So anyone who has persuaded themselves that Cummings’s influence has waned may need to re-think.

Cummings’s pervasive influence was also manifest in the Ditchley Lecture given by Michael Gove this Saturday, which contained more details on Cummings’s long-standing plan to end alleged Whitehall groupthink – by replacing traditional mandarins with data scientists and physicists (or at least supplementing the humanities crowd with those from ‘harder’ disciplines).