Original sentence: On 14 July 2009, the National Portrait Gallery started legal proceedings for breach of copyright against a Wikipedia editor who downloaded thousands of high-resolution images from the NPG website, and placed them on Wikipedia
Edited sentence: On 14 July 2009, the National Portrait Gallery started legal proceedings for breach of copyright against an editor-user of Wikipedia, who downloaded thousands of high-resolution images from the NPG website, and placed them on its sister media repository site, Wikimedia Commons