Sacked aide launches unfair dismissal claim after Dominic Cummings had her frogmarched out of Downing Street

No 10 fears Sonia Khan’s legal action will trigger huge payout – with Boris Johnson himself potentially forced to testify

A former aide who was sacked and frogmarched out of Downing Street on Dominic Cummings’ orders has launched an explosive claim for unfair dismissal.

The legal action launched by Sonia Khan – who strongly denied passing information to Philip Hammond, the former chancellor – could trigger a huge and embarrassing payout by the government.

It will also put renewed focus on the behaviour of Mr Cummings, who must file a formal response within 28 days of Downing Street being served notice of the claim.

And, because Boris Johnson is the ultimate employer of all special advisers, the case could even see the prime minister being asked to testify in Ms Khan’s tribunal.

“She will be able to require them to disclose a lot of information about her employment and the circumstances of her dismissal,” said Beth Hale, a partner at the law firm CM Murray LLP.

“They will have to show that a fair process was followed. I find it difficult to believe that they won’t settle this before a public hearing at which senior figures may need to give evidence.”

Compensation for unfair dismissal is capped at whichever is lower of £86,000 or 12 months’ salary, but Ms Khan is also claiming discrimination – for which there is no limit.

When the adviser to then-chancellor Sajid Javid was walked out of Downing Street by armed police last August, lawyers immediately pointed to the likelihood of legal action.

Mr Cummings claimed Ms Khan had misled him over her contact with Mr Hammond, her former boss, but she denied any wrongdoing – while Mr Javid was not even consulted.

It was pointed out that proper procedures had not been followed, that she was not given the right to be represented and had been humiliated by being bundled out of her workplace.

No inquiry took place afterwards and Mr Cummings, in a subsequent meeting with advisers, is said to have warned: “If you don’t like how I run things, there’s the door.”

The episode was also the first clash between Mr Javid and the controversial chief adviser, which culminated in the chancellor’s sensational resignation on Thursday.

Downing Street is declining to say whether it has been served formal notice of Mr Khan’s claim yet, so it is unclear how long Mr Cummings has to respond.

The legal action comes amid criticism of the hiring of a new adviser who attacked women’s sport and said richer people are more intelligent, after Mr Cummings’ call to sign up “misfits and weirdos”.

Andrew Sabisky also backed giving everyone a mind-enhancing drug – even at the cost of “a dead kid once a year” – and ridiculed the “net zero” climate change target.

Mr Cummings is also understood to have been confronted over his “unkindness” at Friday’s weekly meeting of ministerial advisers.

Some were angry when, at the previous week’s gathering, held before the reshuffle, he remarked at the end: “I’ll see some of you next week.”