The chairman of the UK’s competition watchdog has resigned after just two years in the post, stating the role prevented him leading a more aggressive campaign for change. Andrew Tyrie, who has previously argued UK competition law was not fit for the modern age, will leave the Competition and Markets Authority (CMA) in September. The former Conservative MP and chair of the Treasury select committee – who gained notoriety grilling prime ministers, Bank of England officials and banking chiefs after the 2008 crash – said he had been tasked with designing a “new type of competition authority … better equipped to understand and respond to what most concerns ordinary consumers”. “The government asked me to take this work forward at great pace,” Lord Tyrie said. “I have done so. I now want to make the case more forcefully for legislative and other reform – in parliament and beyond – than is possible within the inherent limits of my position as CMA chairman.” He had “worked hard” to make the organisation “more agile” and “less legally encumbered”, he said. Last year the CMA sought greater powers from government, including the right to fine companies without going to court, but Tyrie is leaving before the changes he proposed are enacted. Tyrie served under Michael Howard as a shadow Treasury spokesman in opposition in 2003-05, but was not appointed to the frontbench by David Cameron. For the majority of his Commons career, Tyrie was a prominent member of the backbench select committees that scrutinise government activities. He sat as chairman of both the parliamentary commission on banking standards and the liaison committee. He was the chair of the Treasury select committee in 2010-17. At the CMA, Tyrie has been a strong proponent of changing the rules so that the watchdog could pursue technology companies who rip off customers. In a 2019 letter to the then business secretary, Greg Clark, he wrote: “Despite relatively recent legislative changes, the UK has an analogue system of competition and consumer law in a digital age.” It now falls to the Department for Business, Energy and Industrial Strategy to find a replacement for Tyrie. The department said: “The day-to-day running of the CMA will continue under its chief executive, Andrea Coscelli, and we will announce next steps on recruitment for a new chair in due course.” Tyrie’s tenure may be short but it has not been without drama. Notable interventions include torpedoing the £7bn merger between Sainsbury’s and Asda that would have created a new supermarket group bigger than current market leader Tesco. He also launched an in-depth investigation into Amazon’s purchase of a stake in Deliveroo but waved it through after the takeaway delivery firm warned it faced collapse because of the coronavirus crisis. Last month he drew the ire of JD Sports by blocking the retailer’s purchase of its struggling rival Footasylum. The decision was described by Peter Cowgill, the executive chairman of JD Sports, as “absurd”.