Denis was appointed official photographer for the 1996-1999 MTV European Music Awards; 2006-2009 Download festivals; Kylie Minogue's 2006/2007 UK Showgirl tour; Prince William and Prince Harry's 2007 Concert For Diana at the new Wembley Stadium, where he took all the official backstage portraits; Glastonbury 2011; and Coachella festival, which he has regularly covered for the organisers. Following the 2016 'Fame Fashion Photography' David Bowie exhibition on London's Heddon Street in aid of Cancer Research, O'Regan took David Bowie, Queen and Punk exhibitions on hugely successful UK tours, attracting over 5000 paying attendees to Q&A sessions.