Isidore Jack Lyons (known before 1991 as Sir Isidore Jack Lyons, CBE; 1 February 1916 – 18 February 2008) was a British financier and philanthropist. After building up a substantial retail business with his brother Bernard Lyons (1913-2008), he was charged in 1987 in the Guinness share-trading fraud. He was convicted and was heavily fined. Subsequent judgments from the European Court of Human Rights held that his trial was not fair. However, the convictions of Lyons and the other members of the Guinness Four were upheld by the Court of Appeal of England and Wales and the House of Lords. Lyons was a significant philanthropist to the arts in Britain for many decades, donating to the London Symphony Orchestra, the University of York, the Royal Academy of Music and the Royal Opera House among