I came across the photos on a visit to Ambalavattam in November 2009. They were hung on the wall in one of the upper rooms inside the padippura. Please click on a photo to see it larger inside a lightbox. I have done some restoration with Photoshop adjustments.
I could recognise Ramakrishnettan. And the parade ground probably is at Madras Regimental Centre, Wellington. The other two persons I have not been able to place.