We are all delighted by the happy news of the arrival of baby Lili,” Prince William and Duchess Kate wrote on their official second child at 11:40 a.m. Friday at Santa Barbara Cottage Hospital.

The new royal addition is named after Queen Elizabeth II, whose family nickname is “Lilibet.” The middle name, Diana, “was chosen to honor her beloved late grandmother, The Princess of Wales,” a release from the couple noted.

other members of the royal family were all traveling on the day Lilibet was celebrating her first birthday at home, but it wasn’t to avoid it.

A source tells ET, the Duke and Duchess of Cambridge and other members of the royal family that included Duchess Sophie and Prince Edward all traveled to different parts of the UK to visit those who are celebrating very happy first birthday. William, Kate and two of their three children — Prince George and Princess Charlotte — later turned up in Wales After the couple announced the birth of their second child, daughter Lilibet “Lili” Diana Mountbatten-Windsor, the Duke and Duchess of Cambridge shared a personal message.