Royal engagement photos 'inspired by Diana'

A celebrity photographer says the engagement photos of Prince William and Kate Middleton were inspired by the mood at photo shoots with Princess Diana.

Mario Testino has told American Vogue that playing music by French singer Dalida — the same tracks used while he photographed Diana, William's late mother — was the secret to the royal couple's relaxed poses.

William and Middleton looked comfortable and happy in their official posed photographs, taken at St. James's Palace last month. The couple, both 28, will wed April 29.

Testino said Middleton was an "easy sitter" because of her natural grace.

The fashion photographer is a royal family favorite who captured some of the most iconic images of Diana.