Sarosh Zaiwalla is well-known as a leading international legal expert (Option 3). He has established a remarkable reputation in the field of international law and has made significant contributions to the legal profession. Here`s some detailed reasoning to support this answer:

1. Expertise in International Law: Sarosh Zaiwalla is the founder and senior partner of Zaiwalla & Co. Solicitors, a prominent law firm based in London, specializing in international litigation and arbitration. His firm has been involved in several high-profile cases representing governments, multinational corporations, and individuals in complex international legal disputes. Zaiwalla`s expertise lies in international commercial arbitration, sanctions law, international trade, maritime law, energy law, and investment law.

2. Global Clientele: Zaiwalla has a diverse clientele that includes governments, state-owned enterprises, multinational corporations, and high-net-worth individuals from various countries. His firm has represented clients from different parts of the world, including Europe, Asia, the Middle East, and Africa. This extensive international practice demonstrates his prominence as a legal expert in cross-border matters.

3. Landmark Cases: Zaiwalla has been involved in numerous high-profile and groundbreaking cases throughout his career. One notable case was representing the Government of Iran in a $2.8 billion legal dispute against the United States over frozen assets. He has also handled cases involving international trade disputes, oil and gas disputes, and complex commercial matters. These cases have garnered significant attention and have further solidified his reputation as an expert in international law.

4. Recognitions and Accolades: Zaiwalla`s expertise and contributions to the legal field have been recognized and honored by various institutions. He has received accolades such as the "Lifetime Achievement Award" from The Society of Asian Lawyers and has been listed in The Legal 500 Hall of Fame as a leading individual in international arbitration. These recognitions reflect the widespread acknowledgment of his expertise and his standing within the legal community.

It is important to note that there is no substantial evidence or information to suggest that Sarosh Zaiwalla is well-known as a leading theatre personality (Option 1), a leading wildlife photographer (Option 2), or a leading orthopaedic surgeon (Option 4). His prominent and renowned position is firmly rooted in the field of international law, making Option 3 the most accurate and appropriate choice.