David Cameron lobbied ministers and senior officials 56 times at the height of the pandemic in an increasingly desperate attempt to beg the government to support a controversial bank he worked for and owned a stake in. The scale of the former prime minister’s chummy lobbying – by text, WhatsApp, email and phone calls – on behalf of Greensill Capital was revealed by Parliament’s Treasury select committee on Tuesday. In one text message, as panic in the financial markets increased at the beginning of the pandemic, Cameron said he was “riding to the rescue … with my new friend Lex Greensill”. In other calls and emails over a four-month lobbying campaign, he told ministers and their adviser that the Treasury’s failure to provide financial support to Greensill was “nuts” and “bonkers”. Cameron often signed off the messages “Dc” or with a simple “👍”. The revelation of the scale of Cameron’s lobbying in support of Greensill came as the UK’s financial regulator said it was “formally investigating” the circumstances leading to the the bank’s collapse. Nikhil Rathi, the Financial Conduct Authority (FCA) chief executive, said some of the allegations facing Greensill were “potentially criminal in nature”. “We are also cooperating with counterparts in other UK enforcement and regulatory agencies, as well as authorities in a number of overseas jurisdictions,” Rathi, added in a letter to the select committee. Rushanara Ali, Labour MP for Bethnal Green and Bow and a member of the select committee, accused Cameron of bringing the position of prime minister into “disrepute” by his relentless lobbying, which she suggested was motivated by personal greed. At a select committee hearing on Tuesday, she accused Lex Greensill, the bank’s founder, of “using a former prime minister, bringing that position into disrepute, to profit”. She added: “You and Mr Cameron lost sight of what was appropriate behaviour. It is a Ponzi scheme, frankly it smacks of fraudulent behaviour.” She added that Greensill’s actions “smacks of the sort of stuff we saw conducted by the likes of [Bernie] Madoff in the financial crisis”. Cameron worked for Greensill as a senior adviser and owned a 1% stake in the bank, which was at one point hoping to float at a $7bn (£5bn) valuation and would have turned the former prime minister into a multimillionaire. Siobhain McDonagh, Labour MP for Mitcham and Morden, asked Greensill: “Are you a fraudster?” in relation the company’s alleged practice of issuing loans against invoices from non-existent customers. He answered: “No, Ms McDonagh I am not … at no point would I or my firm have engaged in financing receivables which we knew to be fraudulent.” Greensill, the son of an Australian watermelon farmer who founded the eponymous bank in 2011 and quickly became a billionaire, travelling the world by private jet, said he took “complete responsibility for the collapse of Greensill Capital”. “I take full responsibility for any hardship being felt by our clients and their suppliers and indeed investors in our programmes,” he said. “To all those affected by this, I am truly sorry.” Cameron’s lobbying to have Greensill included the government’s emergency coronavirus loan support scheme extended to: the chancellor, Rishi Sunak; the Cabinet Office minister, Michael Gove; the health secretary, Matt Hancock; and the vaccines minister, Nadhim Zahawi. He also contacted the economic secretary, John Glen; the financial secretary, Jesse Norman; Sir Jon Cunliffe, deputy governor of the Bank of England; and Richard Sharp, who was then adviser to Rishi Sunak and is now chairman of the BBC. On one day in April 2020, after his requests were turned down by the Treasury, Cameron texted four different ministers. In a message to a senior official he said: “This seems bonkers. Can I have five minutes for a call? Am now calling CX [the chancellor], Gove, everyone.” Cameron has denied breaking any code of conduct or government rules and the government has repeatedly said the outcome of his discussions on Greensill’s proposals for access to a Covid-19 loan scheme were not taken up. One of Cameron’s messages on 3 April 2020 to Gove read: “I know you are manically busy – and doing a great job, by the way (this is bloody hard and I think the team is coping extremely well. But do you have a moment for a word? I am on this number and v free. All good wishes Dc.” On the same day, Cameron sent a separate message to the chancellor asking for a “very quick word” on the Treasury refusal to grant access to the Covid Corporate Financing Facility (CCFF). “HMT are refusing to extend CCFF to include supply chain finance, which is nuts as it pumps billions of cheap credit into SMEs,” Cameron wrote. Cameron told Tom Scholar, the permanent secretary to the Treasury, that he “never quite understood how [interest] rate cuts help a pandemic”. He added that he hoped to “see you with Rishi’s for an elbow bump or foot tap. Love Dc.” On 22 April, the former Conservative leader texted Sunak to apologise “for troubling you again” but asking if he could help on CCFF and if he could “give it another nudge over the finish line”. Greensill Capital, which operated by lending money to firms by buying their invoices at a discount, collapsed in March 2021 after insurers pulled their cover. The collapse has jeopardised 5,000 UK steelmaking jobs, as the bank was key lender to Liberty Steel.