Thanks - looks like it's a very high rank as NCOs go. Her first husband, my great great grandfather, had been a high-ranking NCO (quartermaster sergeant, I think regimental) and a 2nd class police inspector. It was an odd setup because his family were landed gentry in Ireland - the sort of person who, when asked to fill in their occupation on a form, puts "gentleman" - and you would have expected him to be an officer, but it looks like they lost a lot of money through being generous to their tenants during the Great Famine, and couldn't afford to buy him a commission.
I like your sig quote, btw.