The number of congratulatory messages sent by the Queen to people reaching their 100th birthday may have risen by up to a half over the past decade.
An estimated 5,780 people living in the UK were 100 years old in the middle of 2015, according to the Office for National Statistics (ONS).
This compares with 3,710 at the same point in 2005 - a jump of 56%.
When people are approaching 100, it is traditional for their family to apply for a free birthday message to be sent from the Queen.
The figures also show that the total number of people aged 100 and over rose almost two-thirds in the past decade, from 8,850 in 2005 to 14,570 in 2015.
This suggests around one in 5,000 people in the UK was aged 100 or over last year.
ONS statistician Pamela Cobb said: "Although the majority of the very old are women the number of men reaching the oldest ages is increasing as male mortality improves."
The figures reflect the UK's ageing population. In the past three decades, the number of people aged 100 and over quadrupled in number, while those aged 90 and over almost trebled.
There were more than half a million people aged 90 and over in Britain last year - seven in 10 of them female.