The Covid inquiry is hearing much about the key advisers in No 10 when the pandemic struck, and the often expletive-laden messages between them. Some are well known but most are only now emerging from the shadows. Here’s a guide to who’s who: Dominic Cummings Boris Johnson’s chief adviser from July 2019 to November 2020 and his de facto chief of staff. The former Vote Leave supremo has been described at the inquiry as the “most empowered chief of staff Downing Street has ever seen”. His caustic contempt for civil servants and cabinet ministers has been evident in a string of foul-mouthed WhatsApp messages to colleagues. In his evidence he was unrepentant about this and his infamous trip to Barnard Castle. Lee Cain The former journalist, who dressed as chicken for the Daily Mirror during the 2010 election, was No 10’s director of communications when Covid hit. He was said to be briefly running the country, when Johnson, Cummings and many others in government were sick with the virus. A key ally of Cummings, the pair left Downing Street in November 2020 after losing a power struggle with Boris Johnson’s then fiancee, Carrie Symonds. Helen MacNamara The deputy cabinet secretary during Covid and Johnson’s head of ethics. She had led the investigation into bullying allegations against the former home secretary Priti Patel. MacNamara, who went on to work for the Premier League, apologised for her “error of judgment” after she was fined for attending a leaving party in 2020, for which she also provided a karaoke machine. She was the subject of misogynistic rants in messages from Cummings that were shown to the inquiry. Mark Sedwill The former diplomat and career civil servant was the cabinet secretary and head of the civil service when the pandemic struck. Sedwill was forced out by Johnson in September 2020 after being criticised by Cummings, who said he “hasn’t a scooby whats going on”. He also raised alarm by likening Covid to chickenpox. Simon Case The current cabinet secretary was appointed by Johnson to succeed Sedwill, despite his lack of experience running government departments. He had to recuse himself from investigating the Partygate scandal when it emerged that one of the gatherings was held in his office. WhatsApp messages revealed he feared the government resembled a “tragic joke” during the pandemic and that he regarded Johnson as “mad and dangerous”. He is currently on medical leave. Martin Reynolds As Johnson’s principal private secretary, Reynolds was the key gatekeeper and diary holder for the prime minister. He resigned in February 2022 after outrage over Partygate. Reynolds was nicknamed “Party Marty” for organising some of the gatherings in No 10 during the pandemic, including a BYOB (bring your own booze) event. He told the inquiry he could not remember why he turned on the disappearing messages feature on WhatsApp. The Warner brothers Marc and Ben Warner were key allies of Cummings. Ben is a data scientist who worked with Cummings on the Vote Leave campaign. Cummings sent Ben to attend Sage meetings. Marc is the founder of Faculty, an AI company, who was working with NHSX, a joint unit of NHS England and the Department of Health and Social Care. David Halpern A psychologist and founding director of No 10’s behavioural insights team, better known as the “nudge unit”. The unit advised the government on how the public were likely to react to lockdown measures. He used behaviour science techniques to persuade a reluctant Johnson to wear a mask during the pandemic.