One of David Cameron's closest aides downloaded 20 indecent photographs of young, scantily clad girls in sexual poses, a court has heard.

Patrick Rock, 64, who has known the Prime Minister for more than 30 years, resigned from his job in Downing Street after he was arrested when investigators seized his iPad and discovered the images in February 2014.

The girls in the photographs ranged in age between ten and 16, with all but one under the age of 14.

With names such as "cutie" and "princess" the girls were pictured in a variety of what the prosecution said were "sexualised poses".

While all the girls were clothed, most wore skimpy outfits including bras, knickers, bikinis and ballet tutus.

Opening the case for the prosecution, Thomas Forster said it would be up to the jury to decide whether the images were indecent, according to the "propriety of the standards of right minded members of society".