''Granny'' is Warrington woman Lynley Beard (70), who was surprised to find a picture of her daughter's family on the front page of the Otago Daily Times yesterday.
''I went to buy a newspaper ... and got a big surprise when I saw the [story] on the front page,'' Ms Beard said.
Her daughter and son-in-law Jess and Kris Mundy, both formerly of Dunedin, live in Christchurch, where she had been spending her Christmas holidays.
She was yet to speak to her daughter but had heard she was ''highly embarrassed'' about addressing the letter to ''Granny''.
''She has been getting lots of text messages from her friends in Dunedin.''
She was thankful Karitane Store owner/operator Sue O'Neill had persevered in trying to find out who ''Granny'' was. She would pick up the letter on her way back to Warrington from Christchurch in the next few days.
''Granny's'' identity had perplexed the coastal village since the letter arrived at the town's store just before Christmas. Warrington is about 10km south of Karitane.
Ms O'Neill, who was keen to solve the mystery, put the contents of the letter, which included photos of the Mundy family and a Christmas card, beside the counter of the shop, which is also the village's post office.
Ms O'Neill, who yesterday received calls from as far afield as Timaru tipping her off about the mystery, said it was ''absolutely fantastic'' that Granny's identity had been established.
In the end, it was Jack Gibbs who recognised the woman in the photo as his daughter-in-law's sister and called Ms O'Neill.
Mr Gibbs said he was happy to help.
