"A typical unit of the Tigris Flotilla" : A <a href="https://en.wikipedia.org/wiki/Fly_class_gunboat" class="extiw" title="en:Fly class gunboat">Fly class gunboat</a> AKA "Small China Gunboat".
British government
circa. 1915-1918
"British Official" photograph. Downloaded from <a rel="nofollow" class="external free" href="http://www.gwpda.org/naval/tigrisfl.htm">http://www.gwpda.org/naval/tigrisfl.htm</a>