The value placed on the International Baccalaureate by Britain’s university admissions authorities is “potty”, “deeply flawed” and driving students to choose it instead of A levels in the belief it offers an easier path into top colleges, leading headmasters have told the Financial Times.

Under the official weighting designed by the Universities and Colleges Admissions Service the International Baccalaureate (IB or “the bacc”) is given a higher academic rating than A levels.