A British <a href="https://en.wikipedia.org/wiki/British_H_class_submarine" class="extiw" title="en:British H class submarine">H-class</a> <a href="https://en.wikipedia.org/wiki/submarine" class="extiw" title="en:submarine">submarine</a> under construction
unattributed; probably Royal Navy
<a rel="nofollow" class="external free" href="http://www.gwpda.org/naval/pg000000.htm">http://www.gwpda.org/naval/pg000000.htm</a>