Underwood, who first joined the NatWest FX options desk in 1995, has traded a range of FX products on both a proprietary and market-making basis for Deutsche Bank, Standard Chartered, Dresdner Bank and Merrill Lynch. Underwood was offered a place at Oxford at age 14 to study maths, but eventually studied physics, topping his year. Later he completed a PhD in theoretical physics at Imperial College London in just two years. After working briefly as an academic physicist, Underwood left to begin a career in the financial markets.
Most recently, Underwood served as a parliamentary spokesperson for the Liberal Democrats and ran unsuccessfully for a seat in parliament in the 2010 election.