The Conservative MP for Stratford-upon-Avon, 55, started his new job at the Treasury on Wednesday, having previously come under scrutiny for his past dealings with oil companies, medical companies and a tax haven. Before being elected to parliament in 2010, Zahawi was perhaps best known for co-founding the hugely successful research firm YouGov, where he was chief executive until February of that year. After he left YouGov, a company referred to in Companies House documents as “the family trust of the Zahawi family” held £20m of YouGov shares. The Guardian revealed that the company, called Balshore Investments, operated from a law office in Gibraltar. Another Gibraltar-based company, Berkford Investments Limited, lent money to Zahawi to buy an estate and riding stables, now worth £1m, in the village of Upper Tysoe, near Stratford-upon-Avon. Documents obtained from Companies House in Gibraltar showed that Berkford Investments Limited was managed by T&T Management Services Limited, which shares the same address. T&T Management Services Limited’s website advertises its services as trust management for wealthy individuals and families to manage their assets and avoid or minimize paying estate taxes. Once in parliament, Zahawi gained from a second job at Gulf Keystone Petroleum, which paid him £52,325 in remuneration in October 2015 and a monthly salary of £20,000 from October 2015, rising to almost £30,000 a month in August 2017 and around £330,000 in bonus payments. He resigned from the company when he became a government minister in 2018, at which point he received a final payment of £116,000. He also declared stakes in Genel Energy, an Anglo-Turkish oil and gas exploration and production company, and a donation from Amjad Bseisu, chief executive of UK-based oil company EnQuest. Subscribe to First Edition, our free daily newsletter – every morning at 7am. BST More recently, after Zahawi was appointed minister for vaccine development during the Covid pandemic, his wife, Lana Saib, was a director of a medical company, according to Companies House filings. Saib was listed as a 75% plus owner of a company called Warren Medical Limited. The company was incorporated on 10 June 2020 as ‘Zahawi Warren Limited’, before changing a day later to its current title. The company’s two other directors, Ahmad Shanshal and Jaafar Shanshal, are sons of Zahawi and Saib. Asked about the company on LBC radio, Zahawi said it was intended for an ownership deal that never happened and was fully declared to the Department of Business, where he was minister at the time. “I can tell you very accurately that my wife had looked at a project, a real estate project to invest in a brain injury rehabilitation center as a real estate investment,” he said. Zahawi became vaccine minister in November 2020 after serving as business minister for more than a year. Zahawi, often cited as one of the richest members of parliament, said his financial interests had been properly declared to both tax and parliamentary authorities. After taking over as chancellor following the resignation of Rishi Sunak, Zahawi told Sky News on Wednesday that he would review tax policies: “I will look at everything. There is nothing off the table. I want [the UK] to be one of the most competitive countries in the world for investment.” He added: “I know that boards around the world, when they make investment decisions, are looking at the long term and the only tax they can compare globally is corporation tax. I want to make sure we are as competitive as we can be while maintaining fiscal discipline.” A government spokesman said: “Since becoming a minister, the chancellor has declared relevant interests and complied with all the requirements set out in the ministerial code.”