Dev Nagar, the grandson of Maj Gen G R Nagar, with the flag in Pimpri Chinchwad in Pune.
A khadi tricolour hoisted by Pandit Jawaharlal Nehru in Meerut in November 1946 was displayed in public for the first time after 75 years.
Over 5,000 people, many of them students, came to see the flag at a college in Pimpri Chinchwad near Pune during its exhibition from July 24 to 26.
The 9 x 14 feet flag has an image of a spinning wheel and is in the custody of the family of late Maj Gen Ganpat Ram Nagar, the 'general officer commanding' of the third division of Indian National Army (INA) led by Subhash Chandra Bose.
The flag was put up for display to commemorate the 125th birth anniversary of Subhash Chandra Bose, 50 years of the 1971 India-Pakistan war and the Kargil Vijay Divas, Maj Gen Nagar's grandson Dev Nagar told PTI.
Jawaharlal Nehru had hoisted the flag at the Congress session in Meerut in the presence of INA officials.
"The pre-independence Congress session had taken place on November 24, 1946 at the Victoria Park in Meerut where participants included INA functionaries. Pandit Nehru had hoisted the khadi tricolour having the 'charkha' image in the centre," said Dev Nagar, who is the principal of a college in Meerut.
He said his grandfather was given the responsibility of arrangements at that event.
"The flag was brought down on the last day of the session. Nehru and General Shahnawaz Khan from the INA then signed it and handed it over to my grandfather, who was a resident of Meerut, for safe keeping," he said.
The Nagar family has preserved the flag since then. "The flag has been with us since then, safe and well preserved," he said.
According to Dev Nagar, Jawaharlal Nehru had then said that they fought for freedom under this flag and it will be the national flag of the country.
The three colours were retained in the national flag, while the spinning wheel was replaced with the Ashok Chakra, which is a depiction of the Dharmachakra wheel represented by 24 spokes.
Dev Nagar said the family followed the thumb rule of keeping the flag away from dust and moisture during the last 75 years.
"It is always kept folded, packed and sealed with silica gel capsules to prevent moisture. We sometimes keep it out under the sun and then fold it back," he said.
Dev Nagar said he was jittery about the bringing out the flag now as it is a "valuable relic".
He said officials from a Pune institute have offered to conserve the flag. "They said if the flag is properly treated, it can last for another 200 to 300 years," Dev Nagar said.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)