Regards vibrato, interesting... Both my very ancient Irish Great Granny and my Birkenhead Nanna (both now dead) would sing with the most full-throttled, yet butterfly-winged vibrato. Both were extremely ordinary untrained women who simply sang a lot. In fact I think I inherited my own love of singing from Birkenhead Nan. Of course, like most poor people of their generations, they probably visited a few 'picture houses' during their younger years and unwittingly gained some 'aspirational' vocal artiices!?