endowment's assets. The active component of his portfolio outperformed a British equity index by an average of 6% to 8% a year over a quarter century, earning him favourable mention by later investors such as Warren Buffett and George Soros. Joel Tillinghast of Fidelity Investments describes Keynes as an early practitioner of value investing, a school of thought formalised in the US by Benjamin Graham and David Dodd at Columbia Business School during the 1920s and 1930s. However, Keynes is believed to have developed his ideas independently. Keynes also regarded as a pioneer of financial diversification as he recognised the importance of holding assets with "opposed risks" as he wrote "since they are likely to move in opposite directions when there are general fluctuations"; and also as an early international investor who avoided home country bias by investing substantially in stocks outside the United Kingdom. Ken Fisher characterised Keynes as an exception to the rule that economists usually make horrible investors. Keynes joined the Board of the National Mutual Life Assurance Society in 1919, and served as Chairman from 1921 to 1938. Keynes introduced a policy of active trading of the fixed interest stocks, coupled with investment in equities. “Keynes was the first to give [investment trading] the seal of respectability and to apply it to a life assurance fund.” Political life Keynes was a lifelong member of the Liberal Party, which until the 1920s had been one of the two main political parties in the United Kingdom, and as late as 1916 had often been the dominant power in government. Keynes had helped campaign for the Liberals at elections from about 1906, yet he always refused to run for office himself, despite being asked to do so on three separate occasions in 1920. From 1926, when Lloyd George became leader of the Liberals, Keynes took a major role in defining the party's economic policy, but by then the Liberals had been displaced into third-party status by the growing workers-oriented Labour Party. In 1939 Keynes had the option to enter Parliament as an independent MP with the University of Cambridge seat. A by-election for the seat was to be held due to the illness of an elderly Tory, and the master of Magdalene College had obtained agreement that none of the major parties would field a candidate if Keynes chose to stand. Keynes declined the invitation as he felt he