A government review into the Greensill scandal, launched in response to David Cameron’s lobbying attempts, has called for a new code of conduct and greater transparency around who is funding lobbying in Whitehall. The second part of the report, ordered by the prime minister, Boris Johnson, earlier this year and released on Thursday, also recommended the government curb its use of supply chain finance – a method of deferring supplier payments for a fee – that was controversially pushed by Greensill’s bosses and advisers, including Cameron, during the Covid crisis. The review, which was carried out by the corporate lawyer Nigel Boardman, was launched in April after it emerged that Cameron privately lobbied ministers in the hope of securing access to an emergency coronavirus loan scheme for Greensill Capital, the supply chain finance firm that collapsed a month earlier. The extent of the lobbying efforts, which included Cameron contacting the chancellor, Rishi Sunak, on his private mobile phone, were initially revealed by media reports rather than official records. The scandal raised concerns over the way private businesses have been able to hire and use former officials to try to gain preferential access to government contracts. Boardman has recommended in his review that the “transparency of lobbyists be strengthened”, including by “requiring lobbyists to disclose the ultimate person paying for, or benefiting from, their lobbying activity”. A wider array of lobbyists should also be forced to formally register their efforts. Currently, UK rules only require people who lobby on behalf of a company they are not directly employed by to declare their work. Boardman added that any former senior civil servant or minister who engages in lobbying should be forced to register, and that any registered lobbyist should meet a “statutory code of conduct” that sets minimum standards. “I note that, were these recommendations in force at the relevant time, Mr Cameron would have been required to register as a lobbyist,” Boardman said. Boardman also called for the government to broaden the definition of the kind of meeting that must be declared to the public, even if it is not held in person. This could mean that texts and unplanned phone calls, which are not required to be logged under the current ministers’ code of conduct, could end up listed in quarterly lobbying records. The government has also been urged to “improve the management and monitoring of conflicts of interest” in the civil service and make sure that post-employment rules, such as those that ban former civil servants and ministers from taking part in any public contracts or lobbying efforts, be made legally binding. Greensill Capital has been scrutinised for stacking its board and advisory team with an array of civil servants and ministers, including Cameron and the UK government’s ex-chief commercial officer Bill Crothers, before it collapsed. Neither Crothers, Cameron or their former colleagues have been found to have broken any rules. A Cabinet Office spokesperson said the government would “carefully consider Mr Boardman’s recommendations, along with the ongoing work of the committee on standards in public life, and we will respond in due course”.