I am Gran to two, Grandma my other granson.
Gan when they were learning to talk
Other grandmother lives in London and is called Nanny followed by her first name.
I am Gran through choice, given the option by my daughter.
I come from a long. line of Scottish Grans, so to me it would be strange to be called anything other than Gran
However both myself and my 'local to me 'grandsons, have had to get used to others, such as teachers and friends referring to me me Nan or Nanny, which are both common to this area.