(a moggan is a long footless stocking, or a long sleeve for a woman's arm (Scottish and dialect) which is also of obscure origin);
the Gaelic mogan is believed by Celtic philologists to be adopted from Scottish
Cf. mokins dialect ‘gaiters made of coarse sacking’;
also (though the sense is more remote), moggins (Cheshire) shoes with wooden soles, clogs)
see Example below
Or, Some Reflections on His Intrigue with a Young Lass.
William Forbes, 1761