Was Philip de László a secret agent and was MI5's source really as they claimed? Did an enemy spy really paint the portrait of the young Princess Elizabeth? In 1917, noted society portrait painter Philip de László, who painted such luminaries as the Pope, the Austrian emperor, King Edward VII and Prince Louis Battenberg, was subjected to a secret tribunal which interned him for trading with the enemy. At the outbreak of the First World War, de László had pulled strings to be naturalised as British, but in 1919 he was referred to a public committee to revoke his naturalisation. With the aid of skilled counsel, de László had the application overturned – however, newly discovered records show MI5 had evidence obtained from a top-secret source that alleged that he was supplying the enemy with important information on politics and industrial production. Crucially, the source's anonymity prevented MI5 from presenting evidence to the tribunal, which has particular resonance in the contemporary War on Terror. In the only book to examine MI5's secret evidence, Phil Tomaselli explores these allegations and reaches a shocking conclusion.