The 81st were raised in 1777, became the 10th Battalion, 1st Madras Pioneers in the 1922 re-organization of the Indian Army and were disbanded in 1933
Both the 1st/81st and a second, 1917 raised battalion, served on the North West Frontier during WWI, then went to Persia in 1918 to build a railroad and back to the NWF for the 3rd Afghan War, so they were awau from Madras for 6 years. Interestingly, the unit composition included Tamils, some Madrassi Muslims, Chrisitians and 'Paraiyans', a low caste of labourers. A fairly unusuakl mix, even for a southern Indian unit.
The card below, painted by A.C. Lovett in 1911, shows a man of the 81st. He is the fourth from the left - second from the left wearing khaki - and is in service dress.