A special adviser who was escorted out of Downing Street by police on the orders of Dominic Cummings has been given a five-figure payoff by the government. Sonia Khan, a former adviser to the then chancellor, Sajid Javid, is expected to receive the substantial sum after arguing in legal papers that the behaviour of Boris Johnson’s most senior aide was pivotal to her claim of sex discrimination. The disclosure of a payoff weeks before a tribunal was due to be heard will be seen as an attempt by the government to protect Cummings from further controversy. He is set to leave his position at the end of the year, after his close ally Lee Cain resigned as head of communications on Wednesday amid bitter No 10 infighting. Cummings, who sacked Khan last year after claiming she was leaking information, was identified in tribunal documents despite attempts by government lawyers to remove his name. He was also at the centre of a £25,000 payoff to a civil servant in 2012. In a statement released to the Guardian, Khan said: “Following 14 months of negotiation, I have today reached a settlement with the Treasury, my former employer, and as a result I am no longer pursuing my employment tribunal claim, which was due to be heard in London in December.” Khan was Javid’s media adviser when in August 2019 she was escorted from No 10 after Cummings accused her of misleading him over her contact with individuals close to the former chancellor Philip Hammond. She denied any inappropriate contact. Javid was furious to learn about her dismissal after the event. At an employment tribunal hearing in central London, a judge set the case for a five-day hearing in December at which the relationship between Cummings and Johnson would be scrutinised. Khan’s barristers named Cummings as a respondent in the case, which also included an unfair dismissal claim. It is understood the government’s solicitors attempted to argue that his name as a respondent should be removed and replaced with that of the Cabinet Office. Counsel for Khan, who was being supported by the FDA union, argued that Cummings was pivotal to the case and that what he had done personally, rather than just as an agent of the employer, was actionable. He was expected to be summoned as a witness. The hearing ruled that the Cabinet Office could be added as a respondent but Cummings would also remain. Johnson could have been asked to give evidence to the tribunal. At the time of Khan’s dismissal last September, the terms of employment for special advisers made it clear that only the prime minister had the power to sack them. This was changed after Khan left, giving Cummings ultimate “responsibility for disciplinary matters”. Khan, 29, was accused by Cummings of lying about her conversations with Hammond’s former staff member Poppy Trowbridge. It is understood Khan was asked to hand over her work phone, and also presented her personal phone to Cummings. There were no other witnesses to Khan’s sacking by Cummings, who spoke to her in an office in Downing Street close to the prime minister’s. In a meeting days after Khan’s departure with Johnson’s team of special advisers – known as spads – Cummings is said to have remarked: “If you don’t like how I run things, there’s the door.” In 2012, a senior civil servant received £25,000 from the Department for Education in a bullying case she took against Cummings and a senior member of Michael Gove’s team when Cummings was a special adviser in the department. An internal investigation found no grounds for disciplinary action. Cummings also drew criticism for hiring Andrew Sabisky, a temporary contractor who resigned over comments about eugenics and race. Khan thanked the FDA and its legal advisers, Slater and Gordon, as well as the Metropolitan police, “for their support during intense scrutiny and pressure for myself and my family”. She also thanked her current employer, Cicero/AMO, for its “wholehearted backing”. She added: “Having reached a settlement of these issues, I am now moving on with my life and career. I have a fulfilling job as a consultant, I maintain great affection for the Conservative party and remain a committed Conservative. The party took me under its wing when I was a teen and I feel hugely privileged to have served as a special adviser under the last two prime ministers.”