Georgiansilver - would the Jarman you refer to be the William Jarman who eventually settled in the Olympic Peninsula of Washington State? If so, he was hardly an historian in the accepted sense of the term. He was rather like 'Buffalo Bill', much given to creating his own mythology. Given the lack of real evidence, e.g. photos, surviving smocks, or offical documents from the period using the the 'P.O.H.M', I suspect it's alleged origins is one of those apocryphal stories, rather like 'posh' supposedly meaning 'port outwards, starboard home.'