There's an estimated 15,000 people in Britain who have reached the age of 100 and received the famous telegram from the Queen. That's 0.02% of the overall population.
Over five programmes, we hear from some of them about the lives they've led, their experiences in the last 100 years, the lessons they've learned and how they view the future.
Today, Londoners born around the end of the First World War - including Beattie Orwell who reached political consciousness fighting Oswald Mosley's fascists in Cable Street, and Classicist Joyce Reynolds who still researches in Cambridge University library three times a week - consider the "gloomy" state of the world around them and the kind of attitude people need to keep upbeat.
Produced by Alia Cassam
A Falling Tree production for BBC Radio 4 Show less