New Delhi, Aug. 16 -- The chairman of Tata Sons occupies one of the most unusual corporate positions in India.

Tata Sons, along with being a holding company, is the custodian of a group spanning steel, automobiles, technology, power, aviation, hotels, consumer businesses and much else. Above it sit the Tata Trusts, which own roughly two-thirds of Tata Sons and represent the philanthropic purpose and values from which the group derives much of its identity.

The chairman of Tata Sons therefore has to wear several hats. He is the keeper of Tata culture and values, the bridge between the Trusts and the operating companies, an allocator of capital across a vast portfolio, a selector of a few big strategic initiatives, and inevitably an impor...