So confident was bookmaker William Hill in 1997 that it gladly offered Alec Holden odds of 250/1.
But the retired engineer, born April 24, 1907, celebrates his century - to the bookies' dismay.
Mr Holden, from Epsom in Surrey, joked: “I've been very careful about what I've been doing in recent months. If I saw any hooded groups from William Hill standing in the street, I avoided them.”
“Forty birthday cards came for me this morning, including one from the Queen - in fact, I think I saw her delivering it on her bicycle this morning.”
The bet was placed on December 10 in 1997 when Mr Holden was 90.
Mr Holden, who has two sons aged 70 and 60, puts his longevity down to porridge for breakfast and “remembering to keep breathing”.
He also plays chess every day, running a local club, he said.
Mr Holden, who also used to work as a teacher and a carpenter, plans to celebrate by taking some friends to a hotel for a few days.
Meanwhile the out-of-pocket bookmakers have raised the target age for bets from 100 to 110.
Rupert Adams, spokesman for William Hill, said: “When we started taking these bets, 100 years old seemed to be an almost mythical landmark and we were prepared to offer massive odds.
“But these age wagers are starting to cost us a fortune and from now on we are going to push out the age to 110.”
He added: “I am sure that Alec will get more pleasure from our letter than he will from the Queen's.”
