Iwas number three on the day that Sajid Javid and Rishi Sunak began the tsunami of resignations by ministers and office holders that led, inevitably, to Boris Johnson’s demise. In my resignation letter I pointed to a nuanced piece I had written for the Guardian in February. In it, I suggested that should the prime minister quit, he would have been able to do so with his head held high, reflecting on his achievements in office. I can no longer write in those terms. Nothing speaks more to character than the way it is displayed at the end. We learn that in its dying days, this premiership has supposedly taken to bringing down Rishi Sunak, frontrunner in the race to replace the caretaker of Downing Street. Backroom gremlins and hobgoblins – feel for them as they clear their desks – have been putting it about that the former chancellor has been plotting and scheming for months. It’s reported that Johnson has even been urging candidates as they are knocked off the slate to back anyone but Rishi. His chief lieutenants are most certainly at it. At their hands, that most toxic of poisons – the insinuation of betrayal – is eddying around the corridors of Westminster and, its sorcerers hope, will spill from the precincts as the contest reaches the wider Conservative party. Well, I can only speak as I find. Several months ago, when he was riding high, I asked to see the then chancellor. My purpose was to beg him to start an insurgency against the rolling chaos of No 10. In his room behind the Speaker’s chair in the House of Commons, adjacent to the prime ministerial suite, he listened to me in his typically courteous way and felt my pain. But despite every inducement, he remained steadfastly loyal to Boris Johnson. My purpose thwarted, I left the meeting disappointed but with my high opinion of this remarkable man strengthened even further. A domain registration hardly constitutes a hostile bid for the boss’s job, and if that’s all his critics can unearth as evidence of disloyalty, I confidently rest my case. This bloke, I concluded, could be relied on to play a straight bat. In contrast, a few weeks later, one of the other candidates who subsequently threw their names in the hat invited me in for a fireside chat. Wild horses will never drag from me that colleague’s name, but the purpose was to enlist my support for a campaign for the leadership that was plainly already well advanced. Now I don’t condemn my colleague for one moment in feeling compelled to act. After all, major political parties in sophisticated western democracies should never become vehicles for the outrageous personal ambition of individuals, however charismatic. They must never become personality cults. Parties exist to advance ideas and policies for the greater good, not the careers of individuals. Loyalty is to the team, and to the conviction that it is best placed to advance the welfare and wellbeing of those we are privileged to serve. My party has, belatedly but nevertheless, begun the process of dealing with a situation that had become intolerable. In my view, it is our individual and collective duty to do so. My unnamed candidate colleague recognised that. At the turn of the year, that person was doing precisely the thing I was pressing on Rishi Sunak. I’m in no doubt that the former chancellor’s hand was stayed by his loyalty to the prime minister. But ultimately it is loyalty to the cause we serve and country that matters and that’s what we saw playing out a fortnight ago. Attention now shifts to my party’s membership. But, frequently underestimated and misunderstood, they will be watching to see how the two candidates go down with the wider public before making their mark. After all, they want to win in 2024. In my constituency, as elsewhere, weathering a global economic downturn and taking the edge off the consequent cost of living crisis is the central challenge. I trust the man whose swift and substantial action saved so many small businesses in my patch during the pandemic, whose interventions continue to prioritise my less well-off constituents and who, post Brexit, represents our best, fiscally responsible chance of breaking the chains of sluggish growth and indifferent productivity. That’s why I’m backing Rishi Sunak. Andrew Murrison is the Conservative MP for South West Wiltshire, and a former minister of state for the Middle East