Da Cunha started his advertising career in 1951 at L. A. Stronach Advertising, a British advertising agency. He worked in their London liaison office for three years before returning to India. On his trip back on the boat he was offered a job by John Kurien, a manager with the
Birla group's Advertising and Sales Promotions (ASP) agency. At ASP, da Cunha initially handled some of the Birla group's inhouse brands like
Hindustan Motors and Century Rayon, before handling accounts including
Life Insurance Corporation,
Glaxo and
Lakmé. Da Cunha teamed up with illustrator and art director Eustace Fernandes to create the ads. The ads had a mischievous looking girl in a white dress with red polka-dots and blue hair, poking fun at major celebrities and newsmakers. They were noted for their news topical relevance and tongue-in-cheek wit and humour. It was one of the longest running campaigns in India, and remained active at the time of da Cunha's death. The campaign and the mascot was noted to have been in response to the incumbent market leader
Polson butter, who had a similar mascot of a girl who was soft and well-mannered. This prompted da Cunha to model the Amul girl as a mischievous girl taking a dig at ongoing current events. Da Cunha later went on to found his own advertising company Da Cunha Associates in 1969, after spending 14 years at ASP. Da Cunha handed over creation of Amul's topical advertisements to his son Rahul in 1993. The campaign holds the
Guinness World Record for the longest running advertising campaign. Da Cunha was also involved in English language theatre in India. He was a founding member of the Theatre Group of Bombay. He was among the first to combine Hindi and English language into plays, which was not common at the time. Some of his popular plays included
I love Mumbai,
It is not funny!, and
Topsy-Turvy. He also directed and acted in an adaptation of
Vijay Tendulkar's
Kamala. In the 1980s and 1990s, da Cunha was also part of various social development initiatives. During this time, he served as a population and nutritional consultant with the Information, Education, and Communication unit of the
World Bank, traveling within India, and to various countries including Brazil, Turkey and Zambia. He also served as a consultant to the
UNICEF and the
International Bank for Reconstruction and Development on food and nutrition projects. == Personal life ==