This is a fascinating, relatively rare, cover(using a unit envelope!) from a soldier(likely an officer) of the 1st Battalion, 13th Regiment of Foot, Somerset Light Infantry, on November 3, 1900! That battalion was most likely in either the North West Frontier Province, or Rawalpindi at the time that this mail was sent. The mail arrived in Plas Newydd, Weston Super Mare, Northern Somerset, on November 24, 1900!  

To continue, the brown, 1-a. GB British India stamp used to pay the soldier's concession rate is in fine condition! The, "Camp Post Office," CDS is quite excellent, but was smudged some upon application. The receiving cancel from the Weston Super Mare P.O. is superb!  

Lastly, as for the envelope, itself, it's in pretty good condition considering its age and how much it has travelled! It does have some toning and other types of stains here and there, mostly around the edges and back. There are some tears along the top and bottom of the front, and some in the back flap connected to how the mail was originally, somewhat-roughly, opened. The back flap is 85% complete. Noted blemishes aside, this is a really neat, uncommon piece of early 20th Century, British military history connected to the 1st Battalion, 13th Regiment of Foot, Somerset Light Infantry!