According to the book "Motoren" by Helmut Hütten (german language) stirling engines were developed on a industrial basis in the 1930ies by the dutch Philips electrotechnical group. They wanted a quiet, long-living power generator working on various fuels for their radio applications. The development became obsolete when radios no longer used power consuming vacuum tubes.

Even the best and most advanced stirling types are much less efficient than diesel engines or even gassers, they are only of interest when heat is free or the main purpose of a combustion process is heat generation, and electrical power is generated aside.

Sure the stirling principle is fascinating, and the most astonishing aspect is that is was invented long before the thermodynamis behind it were even roughly understood.