Your editorial (13 November) was spot-on and made me realise that Dominic Cummings’ influence on this Tory government and on the country will for ever be linked in my mind with the arc of the Covid pandemic. In the same way that a coronavirus requires a human “host” to thrive and spread, so Cummings needed politicians susceptible to infection by his poisonous and destructive ideology to gain a position of such power and influence. Michael Gove was the man who introduced him into the Tory machine, appointing him as his special adviser when he was secretary of state for education. When Cummings was his adviser, Gove insulted teachers and lecturers, and removed schools from local control to place them in often large academy chains. So unpopular did Cummings’ “host” politician become with the public that David Cameron demoted him, believing Cummings responsible for “dripping poison” into Gove’s ear. It was entirely typical of the reckless style of Boris Johnson that he reintroduced Cummings into the heart of his government, where he presumably encouraged his new “host” to disrupt the civil service, illegally prorogue parliament, attack judges and threaten the BBC. It is no doubt more than partly due to his influence that his “host” has failed to respond effectively to a national health crisis and to prepare the country for the double whammy of an economic recession and a looming crash-out from the single market. The announcement of a Covid vaccine offers hope, and so does Cummings’ departure from Downing Street. However, just as a vaccine won’t undo the damage wreaked by the virus over the past year, so this government and the country will take a long time to recover from the poison Cummings has injected into its most important structures and arteries. Chris Dunne London • The key issue with political advisers in the prime minister’s office (Boris Johnson boots out top adviser Dominic Cummings, 13 November) is not so much who does what job, but their relative power and influence compared with that of the civil service. The government’s code of conduct for special advisers states that their role is to “add a political dimension to the advice and assistance available to ministers”. They complement civil servants but don’t substitute for them. They don’t have executive responsibilities. In No 10, the obverse appears to apply. At least three special advisers but only one civil service adviser routinely have direct access to the prime minister, the latter being the cabinet secretary, who – with only 12 years’ experience of the service – is a comparative rookie. This imbalance borders on the unconstitutional, and almost certainly explains the Johnson government’s indifferent performance on the pandemic and in the Brexit negotiations. Robin Wendt Chester • “It’s like a Mexican firing squad in there,” says a “government adviser” about 10 Downing Street (Lee Cain’s departure is only the beginning in the battle for control of No 10, 12 November). Just for the record, Mexico does not permit capital punishment and the last execution by firing squad was some 60 years ago. Maybe this is a garbled filmic image harking back to the Mexican revolution of 1910, when such executions were common. But they were, in fact, conducted as orderly performative rituals and were not frenzied factional shootouts. So, nothing like Downing Street. Alan Knight Emeritus professor, St Antony’s College, Oxford • Are there certain occupations where, on appointment, you are issued with a collapsible cardboard box? I am particularly thinking of bankers and political aides. Most of us, on learning that we had to clear our desks, would be scrabbling around for an old carrier bag. Anne Plunkett Halifax, West Yorkshire • Friday was World Kindness Day. To mark it, Dominic Cummings left his Downing Street role. I can’t think of a more altruistic act. Tim Ottevanger Lutterworth, Leicestershire • So how long before we see Lord Cummings and Lord Cain? Stephanie Bailey Norton-sub-Hamdon, Somerset • Join the conversation – email guardian.letters@theguardian.com • Read more Guardian letters – click here to visit theguardian.com/letters