I like it.
Lower middle class north-western upbringing here and all my mum's mates were Aunty to us - we just seemed to slip out of it around 16ish and they became known by their first names, which by then seemed a natural progression. No confusion re who I was related to or not, it was very widespread.
Still called the elderly lady who lived next door Mrs X though, even when we were older and she said 'oh, call me Y' - it just seemed really odd and disrespectful to call someone so much older than us by her first name.
Fraightfully upper MC friend brought up in Kent referred to herself as 'Aunty L' to DD more or less as soon as she was born and I'm 'Aunty FB' to her DCs, similarly my vair, vair upper class drama friend who's grandma owns half of Wiltshire introduced herself to DD as 'Aunty S', so I doubt it's a class/regional thing at all. We're all in our late 30's/early 40's, perhaps it's a generational thing?
Having just hosted a playdate where I was constantly referred to as 'DD's Mum' when the 4 yr olds wanted my attention, I'd rather like being Aunty Fruitbeard...
Makes my teeth itch when a random child calls me by my first name!