It is unclear from which of the many British campaigns in Waziristan, Northwest Frontier Province (NWFP, now Khyber Pakhtunkhwa) on the border with Afghanistan this postcard of an early armored car is from. There was a major campaign in 1919-1920 after the 3rd Afghan War, which continued 1921-24 around Razmak, then another in 1924-25 in South Waziristan which culminated in an early Royal Air Force (RAF) campaign. It is likely that the postcard is from the early 1920s, though there were more campaigns between 1936 and 1939.
K.C. Mehra would have been a war photographer who accompanied British and Indian troops fighting in these campaigns, and would have made photographs for private albums of the regiments and officers involved, and had the rights to turn them into postcards.