Special adviser Cleo Watson
is understood to have handed in her resignation yesterday, a fortnight after the maverick No10 chief departed.
The exit underlines the waning hold of Vote Leave veterans over the heart of government, as Boris Johnson
tries to 'reset' his premiership.
worked on the Brexit campaign before joining the No10 operation under Theresa May
, and taking a more senior role when Mr Johnson
Although the 31-year-old's official title is "Head of the PM's Priorities and Campaigns", she has been known as the 'the Cummings whisperer' due to her reputed ability to calm him down.
The pair were regularly seen walking into Downing Street together in the mornings, with Ms Watson's
smart appearance in stark contrast to Mr Cummings
' shambolic style.
There had been hopes that Ms Watson
would opt to stay on in her post, as she was not regarded as being deeply involved in the extraordinary civil war.