“Delhi is not actually a state but the NCT. So the 2001 Census only included the NCT population. The census count stood at 1,38,50,507, but since rural population is not included, the Delhi UA population was 1,28,77,470,” said Sharma. In comparison, the Census put Mumbai’s population at 1,64,34,386 and Kolkata’s at 1,32,05,697.

According to the study, the actual population of Delhi Metropolitan Area, which includes the neighbouring towns of Haryana and Uttar Pradesh, should have been 1,62,36,397 in 2001. While this still puts the national capital in second place, the estimated figures for 2007 puts Delhi at 2,20,80,001, much higher than Mumbai’s estimate of 1,94,38,973.

Joint Director of Census Operations Babu Lal admits that the study may be right. “But in India, we are bound by the definition of an urban agglomeration, in which we cannot cross state boundaries. If we do so, Delhi is actually the biggest city in India,” he said.