This is Travancore SG 31. The normal watermark on these stamps is sideways. If the watermark is upright, you have SG 31b - quite a rare stamp.
With the heavy folding, the value of the sheet is severely devalued. Still, I'd expect a price in the low double figures for it on
ebay (assuming it's only SG 31; all bets are off if it's SG 31b

)