Boris Johnson rocked by further resignation, the day after losing four key aides

• Elena Narozanski quit Downing Street's policy unit on Friday morning.
• Four key aides left Downing Street Thursday, further piling pressure onto Boris Johnson.

Boris Johnson's premiership was rocked by the departure of another adviser Friday, following the departure of several key Downing Street aides.

Elena Narozanski, a member of the Downing Street policy unit, has resigned, according to Conservative Home's Paul Goodman. She was Johnson's special adviser on women and equalities, Department for Culture, Media and Sport, and extremism.

Her departure follows the resignation of four key Downing Street aides on Thursday.

Munira Mirza, the prime minister's policy unit chief,quit abruptly citing Johnson's refusal to apologise for using a conspiracy theory to try and smear Labour leader Keir Starmer. She had worked for the prime minister for 14 years, dating back to his time as Mayor of London. Her decision to leave Number 10 is widely seen as damaging for the prime minister, who is battling allegations that he oversaw a culture that led to repeated breaches of COVID-19 rules.

On Thursday evening, three other Downing Street aides resigned.

Jack Doyle, the director of communications, Dan Rosenfield, the chief of staff, and Martin Reynolds, the prime minister's principal private secretary, had all been criticised in recent weeks.

Greg Hands, the energy minister, insisted these three resignations were part of a "shake-up" at Number 10 which Johnson promised this week.

But Lord Barwell, who was chief of staff under Theresa May, said: " I don't think he would have wanted to lose Munira… The terms of her letter yesterday were completely damning.

"We've long speculated about whether the problem in Number 10 wasn't getting sensible advice or that he was getting it and he wasn't listening to it. And what we learnt yesterday is that at least in relation to the appalling smear of Keir Starmer on Monday, he was told very clearly by aides not to do it, and still went ahead."

Nikki Da Costa, a former senior Downing Street adviser who worked with Mirza, said: "There have been long-running issues within Number 10. In that circumstance it can be very difficult to be a strong adviser and to have impact."

Rosenfield had failed to build a positive culture when he arrived in January last year, Da Costa added.

"Morale has been undermined and certainly there has been a culture in which if you aren't somebody that says yes and falls into line, then you quickly find yourself marginalised," she said.