Half an hour before I am due to have lunch with Arvind Kejriwal, leader of India’s fledgling Aam Aadmi (literally “Common Man”) party, my appointment is cancelled. A day earlier, the tax collector turned social activist had been out campaigning in the parliamentary elections when the driver of an auto rickshaw slapped him across the face. It was just the latest physical blow landed on the 45-year-old Kejriwal, who refuses to have the heavily armed guards who shield many Indian politicians.

Instead of our rendezvous, Kejriwal, with media in tow, travelled to a distant corner of Delhi to visit his assailant, who offered a grovelling apology and was forgiven. It was the kind of headline-grabbing stunt at which Kejriwal excels, gaining him free TV airtime during India’s protracted general election, the world’s biggest, with more than 800m voters whose verdict will be revealed on May 16.

Such publicity coups are crucial for a campaign running on small donations. Kejriwal’s AAP is challenging deep-pocketed establishment rivals: Rahul Gandhi’s ruling Congress party and the Hindu nationalist Bharatiya Janata party (BJP) of Narendra Modi, the expected beneficiary of strong public disillusionment with Congress.