Ahead of Ratan Tata's last day as Chairman of the Tata Group, we speak to Kiran Mazumdar Shaw, chairman and managing director of Biocon, Patrick Foulis, Editor of India business and finance at The Economist and Firdose Vandrevala, chairman and managing director of HIRCO separately about what makes Ratan Tata such a legendary industrialist, his contribution to Indian business and the lessons he taught his corporate peers.