The Princess of Wales has spoken of her pride in the Irish Guards as she wrote to apologise for missing a parade rehearsal on Saturday.
Catherine would usually attend the so-called Colonel's Review - held before next week's Trooping the Colour - but is taking time away from her official duties after treatment for cancer.
In a letter signed Colonel Catherine, the princess said it was a "great honour" to be the group's ceremonial leader, and that she hoped to "be to able to represent you all once again very soon".
In March, she revealed she was receiving treatment for cancer, discovered in post-operative tests following abdominal surgery in January.
Last week, a Kensington Palace spokesman said: "The princess is not expected to return to work until it's cleared by her medical team."
Catherine has not attended any official events since Christmas.
The Irish Guards posted a video on X, formerly Twitter, showing her letter being read to members of the regiment.
"The Irish Guards were deeply touched to receive a letter from our colonel, Her Royal Highness, the Princess of Wales this morning," it said in the post.
"We continue to wish Her Royal Highness well in her recovery and send her our very best wishes," it added.
The Trooping of the Colour, due to be held on 15 June, has marked the King's birthday for more than 260 years.
Traditionally it sees the Royal Family gather on the balcony of Buckingham Palace.
King Charles has confirmed that he will take part despite also undergoing cancer treatment.
Last year, the King inspected troops from horseback during the event, which is filled with pomp and military pageantry.
This time, he will conduct the review seated in an Ascot Landau carriage with Queen Camilla.
