December 12: Last day for four NZ Prime Ministers

Sir Keith Holyoake, a former Prime Minister of New Zealand also stepped down on 12 December. Photo / File

Today is Prime Minister John Key's last day in the top job.

But it turns out December 12 was also the last day in office for three other New Zealand prime ministers.

Key's term officially ends today, after he took up the position in November 2008.

He joins a list of former leaders who also passed on the reins on the same date.

• Sir Keith Holyoake became the country's 26th Prime Minister in 1957. He had a brief term between September 20 and December 12.

• Sir Walter Nash took over as Prime Minister from December 12, 1957, and finished his term three years later, again on December 12.

• Sir Wallace Rowling, widely known as Bill, became New Zealand's 30th Prime Minister on September 6, 1974. His last day in office was December 12, 1975.

Aside from soon-to-be Prime Minister Bill English, the only other leader who has a connection with the date is Sir Robert Muldoon, who succeeded Rowling to become the country's 31st Prime Minister.

A spokeswoman for Key said he would not be commenting on any media stories for the rest of the week, but acknowledged it was probably a coincidence.

Political scientist Dr Bryce Edwards, of the University of Otago, said there was no set date a Prime Minister had to step down, but that it was most likely because it was near the end of the year, when things needed to be sorted out.

"I think it's not a coincidence that it is in December. But the fact that it's the 12th is probably a coincidence.''

Edwards said it was widely known that Key regarded Holyoake as a significant influence on him and his leadership style.

The same departure date is likely to be a nice surprise for Key, Edwards said.

"It's a nice historical parallel and something that Key is probably not aware of yet but something he will appreciate.

"He will be flattered with that parallel, I think.''

Interestingly, Prime Minister Jenny Shipley's term in office finished on December 5, 1999, and Labour leader Helen Clark was named the PM that day; the same day Key would announce his shock resignation 17 years later.

December 12 in history:

1792: A certain pianist receives his first lesson in music composition. His name is Ludwig Von Beethoven.

1800: Washington DC is established as the capital city of the United States of America.

1963: Frank Sinatra jnr, son of the American singer, is returned after being kidnapped for ransom.

2015: First woman ever elected in Saudi Arabia in municipal council elections.