The Anglican Diocese believes the font could be Norman, and up to 1000 years old, but its age has not been verified.
Diocese spokeswoman Emma Neas, of Dunedin, said the church believed the font was brought from France to England at the time of the Norman conquest of England (1066).
It understands the font sat unused in an unknown church's crypt for 200 years, until it was bought by Bishop Samuel Nevill, who intended it for the Dunedin Cathedral.
But the font was not deemed big or fancy enough for the new cathedral, and was instead installed in Lawrence.
The last service was held at the Holy Trinity, which is being decommissioned, on January 11 and the ''ugly duckling'' font could once again be temporarily left without a home, she said.
Milton-Tuapeka vicar the Rev Vivienne Galletly said the stone the font was made of was one of the tell-tale signs of its age.
She understands it is Caen stone, which could indicate an 11th century, perhaps Norman origin and its simple shape is like earlier designs, she said.
Significantly, the bowl of the font was much larger than more modern fonts, she said.
''You can bathe twins in it.''
The size indicated a very early practice of fully immersing babies during baptism.
She said William Richardson Mayhew wrote in 1949 in Tuapeka: The Land and its People, published as part of an Otago Centennial Historical Publications series, that the font was found in a field near a church that was destroyed in 1640, but the story was most likely to be a repetition of a story the church told.
''There's no footnotes. I would suggest he's just retelling, and prepared to believe, the parish story.''
Miss Galletly has performed four baptisms at the font.
Mrs Neas said a decision was yet to be made about where the font would end up, but it was likely to stay in a church within the diocese, which covers the area from North Oamaru to Bluff.