The man appointed by Boris Johnson to rule over the Greensill lobbying scandal is on the board of a private bank that has close ties with the Conservative party and has a number of former civil servants in its ranks, the Guardian can reveal. The position held by Nigel Boardman with Arbuthnot Banking Group has raised concerns among anti-corruption campaigners that his inquiry could be undermined by the perception of bias. The bank specialises in managing money for the wealthy and is chaired and majority owned by one of the largest donors to the Tory party, and one of its former treasurers, Sir Henry Angest. Arbuthnot has also stacked its boardroom with former government staffers, including the former British ambassador Christopher Meyer, the former Tory MP and Treasury minister Angela Knight, and – until January – Baroness Finn. George Havenhand, a senior legal researcher at anti-corruption campaign group Spotlight on Corruption, questioned Boardman’s ability to independently scrutinise Greensill Capital’s influence on government officials, given his own links to Arbuthnot, which has also recruited a number of former public servants. “As a director and shareholder in a bank that itself has deep political affiliations and is riddled with the revolving door, we have real concerns that Boardman is too close to the industry to be truly objective and independent in this investigation,” Havenhand said. Boardman currently holds about 11,345 shares in Arbuthnot, worth around £132,204. “We have serious concerns that the appointment of Nigel Boardman to lead the inquiry into the use of supply chain finance in government was done in haste and without appropriate assessment of potential conflicts of interest, whether perceived or actual,” Havenhand added. The Cabinet Office denied that there was any conflict of interest. The Greensill Capital lobbying scandal has raised concerns over the way private businesses are able to use former officials to try gain preferential access to government contracts. The supply chain lender, which collapsed last month, recruited a number of political heavyweights and Westminster officials, including the former prime minister David Cameron, former home secretary David Blunkett, former homelessness tsar Dame Louise Casey and the government’s former chief commercial officer Bill Crothers. There is no suggestion of wrongdoing by the Greensill appointees. The scandal was prompted by revelations that Cameron had lobbied a string of Whitehall officials last year – including texting the chancellor, Rishi Sunak – in hopes of securing Greensill access to the UK’s largest emergency Covid loans scheme, which would have involved bending the rules. He also took its founder, Lex Greensill, to a “private drink” with Matt Hancock, the health secretary, in 2019 to promote the company’s wage advance app, Earnd, for use in the NHS. On Tuesday, it emerged that Crothers had joined Greensill while remaining a civil servant – in a move sanctioned by the Cabinet Office. The news prompted alarm within No 10, and concerns were raised further on Thursday that a second Cabinet Office adviser, David Brierwood, had been hired by Greensill while still working inside Whitehall. Meanwhile, one of Arbuthnot’s former advisers, Lawrence Weiss, simultaneously worked as a non-executive director of UK Export Finance – a government credit agency – until he resigned from the advisory role in September 2020. It adds to the growing list of government officials facing scrutiny for straddling public and private sector interests. The shadow chancellor of the duchy of Lancaster, Rachel Reeves, said: “Claims that the Boardman investigation is independent are lying in tatters. “The more that serious questions like these emerge about Boardman, the more it looks like the Conservatives are set on glossing over cronyism in their ranks, so they can carry on like nothing has happened.” Boardman’s investigation, announced on Monday, will look at the development and use of supply chain finance offered by Greensill, and its associated activities in government. Arbuthnot Banking Group, which appointed Boardman as a director in mid-2019, is also known for providing financial support to the Tory party. It has made combined donations worth at least £412,975 to the party and its members, including David Davis and Dominic Raab, since 2005, according to Electoral Commission records. Angest, its chief executive and chairman, has been a major supporter, offering at least £7m in loans and donations. The Cabinet Office said in a statement: “Nigel Boardman is a distinguished legal expert and he was asked to lead this review following his own declaration of interests. It would be wrong to suggest there is a conflict of interest. “The review will examine the facts thoroughly.” An Arbuthnot Banking Group spokesman said: “As one of the leading corporate solicitors of his generation with deep financial services experience and having served as a partner of Slaughter & May for nearly four decades, the value he provides to the bank and its governance should be self-evident. “Separately, Arbuthnot Banking Group’s political donations are entirely appropriate and are a matter of public record.”