As a minister, Margaret Hodge never convinced; as chair of the public accounts committee she has shone. The PAC has long been, as Professor Peter Hennessy says, “the queen of the select committees”, terrifying government departments and agencies. But Ms Hodge’s innovation, since taking the chair in 2010, has been to focus on a private-sector problem: tax avoidance. Since Christmas, the PAC has laid into Google, Starbucks and Amazon for their “immoral” use of loopholes to duck paying tax. She has allied her frontbencher’s instinct for where public interest lies with a backbench pugnacity. Today’s hearing of the Big Four accountancy firms summed up the Hodge style. Platitudes about customer service were cut short with a bark – and a tetchy demand that the suits get to the point. This was no mere showmanship, but produced that an unlikely thing: a sparky and informative conversation about accountancy.