The Duke of Edinburgh has joked that “bits are beginning to drop off the ancient frame” as he approaches his 90th birthday.

Writing in acknowledgement of being named an Oldie of the Year, Prince Philip told organisers he was unable to attend the award ceremony, but added that it was “nice to be remembered”.

The Oldie magazine received the letter after inviting the Duke to today’s event celebrating those of an advanced age.

Prince Philip, who turns 90 in June, has been named by the magazine as Consort of the Year.

Last year the Duke announced that he was planning to scale back on his responsibilities.

But royal aides have stressed that he is “still very busy” and “still very active”.

And in the letter to The Oldie, the Duke shows he has not lost his sense of humour.

Signed “Philip” and written on Sandringham House headed notepaper, he wrote: “I much appreciate your invitation to receive an Oldie of the Year Award.

“There is nothing like it for morale to be reminded that the years are passing – ever more quickly – and that bits are beginning to drop off the ancient frame.

“But it is nice to be remembered at all.”