Boris Johnson ally Simon Case poised to be named head of civil service

Relative outsider expected to be named as cabinet secretary, replacing Sir Mark Sedwill

The government is to unveil its new top civil servant on Tuesday to replace Sir Mark Sedwill, who stepped down following hostile briefings linked to No 10, with a 41-year-old outsider closely allied to Boris Johnson expected to be named.

Simon Case, a former private secretary to Prince William who was seconded to No 10 in May at the prime minister's request, is to be formally announced as the new cabinet secretary, the Financial Times said, citing three unnamed sources.