Former Lloyd's chairman Sax Riley died over the weekend, at the age of 62.
Lloyd's will ring the Lutine Bell today at 3pm as a mark of respect for the former Lloyd's chairman and Sedgwick chief executive.
Lloyd's CEO Nick Prettejohn said: "All those who knew and worked with Sax will be shocked and devastated by this news. Sax was held in high regard and affection, and I considered it an honour to work with him.
"His chairmanship of Lloyds brought historic reform and outstanding leadership through the difficult times after the tragedy of 9 /11. He was a determined, cultured and intelligent man with a wonderful sense of humour and a splendidly forthright style. He will be sorely missed, and our thoughts are with his family."
Riley was chairman of Lloyd's until last year, when his successor, Lord Levene, took over.
