Vote Leave veteran follows Dominic Cummings out of No 10

Prime Minister Boris Johnson's key adviser Dominic Cummings and his assistant Cleo Watson arrive in Downing Street - Credit: PA

Another Vote Leave veteran has walked out of Downing Street following the resignation of ally Dominic Cummings.

Special adviser Cleo Watson handed in her resignation to Number 10 just weeks after former Vote Leave mastermind Cummings and communications expert Lee Cain resigned.

Watson worked on the Brexit campaign before joining government under Theresa May, before taking a senior role under Boris Johnson, assisting the key aide in many of his duties.

Cummings was reportedly hoping to make Watson – described as his protégé – chief of staff in the latest Downing Street reshuffle after her old sister Annabel operated in the role in May’s office between 2006 and 2010.

The exit of Watson, Cain and Cummings came after Johnson’s partner Carrie Symonds and Allegra Stratton, the prime minister’s press secretary, argued the PM had been poorly advised.

There is speculation the departure of the key Vote Leave allies is a sign Johnson is planning to agree to a Brexit deal which may not meet their approval in the coming days.

The Times reports that such a move could also see Sajid Javid reinstated in government after being forced out by his advisers earlier this year.