LONDON, Thursday 29 July 2010 (AFP) - A set of dentures made for Britain's war-time prime minister Winston Churchill known as "the teeth that saved the world" sold for nearly 18,000 pounds (21,500 euros, 28,000 dollars) at auction Thursday.

The false teeth -- which were specially designed to preserve Churchill's natural lisp on morale-boosting radio broadcasts he made during World War II -- fetched over three times their pre-sale estimate.

They were snapped up by a private collector from Britain who paid 15,200 pounds, or 17,879 pounds including commission, said a spokeswoman for auctioneers Keys of Aylsham in Norfolk, eastern England.

Before the sale, Keys had estimated they would fetch up to 5,000 pounds.

The false teeth were being sold on behalf of Nigel Cudlipp, son of the man who made them.

Cudlipp recalled the story of how Churchill used to vent his frustration when the 1939-45 war was not going well by flicking the dentures out of his mouth, in an interview with BBC radio Thursday.

"My father recounted many stories of Churchill putting his thumb behind the front of the teeth and just flicking them," Cudlipp said.

"My father used to say he could tell how well the war effort was going by how far they went across the room and whether they hit the opposite wall.

"Churchill was not a man who was renowned for his patience."

It is thought that only four sets of the dentures were made. One is believed to have gone to the grave with him, another is in a London museum labelled "the teeth that saved the world" and a third was melted down.

Meanwhile, it was announced Thursday that a huge archive of Churchill's personal papers is to be made available on the Internet for the first time within two years.

This includes around a million pages of material such as annotated drafts of his most famous speeches, school reports and even information about his cat, dogs and pet budgerigar Toby.

"Churchill was someone who lived by his pen so this is an incredibly rich written archive and it must be one of the largest personal archives of its kind in the country," Allen Packwood, director of the Churchill Archives Centre in Cambridge, told AFP.