Frank Hahn had a transformative impact on British economics wherever he went, building on his love of, and competence in, mathematics and greatly influenced by his numerous American colleagues. He was at the heart of the development of General Equilibrium theory, which he criticised for its inability to include money. As a mathematical economist he was aware of the power of maximisation to deliver testable propositions about competitive equilibrium, but he was also sceptical about competitive equilibrium as a useful description of any actual economy. Later he was to attack what he termed Lucasian macroeconomists (Robert Lucas and his followers) for assuming that economies were in competitive equilibrium. His published works live on along with his huge impact on the profession. He brought together and worked with the best economists of his generation, nurtured and launched his students and colleagues, and, crucially, introduced the modern American rigorous theoretical economic approach to the more literary-minded and even anti-mathematical English style that had been prevalent since Marshall.
