I love you in all the languages in the world ("Ti amo in tutte le lingue del mondo") is a 2005 film directed by and starring Leonardo Pieraccioni.
Catch Me If You Can: Music from the Motion Picture is the original soundtrack of the 2002 film of the same name, starring Leonardo DiCaprio, Tom Hanks, Christopher Walken, Martin Sheen and Amy Adams.
 The original score was composed by John Williams.
 The film was the twentieth collaboration between Williams and director Steven Spielberg.
Blood Diamond is a 2006 German-American political war thriller film co-produced and directed by Edward Zwick, starring Leonardo DiCaprio, Jennifer Connelly and Djimon Hounsou.
 The title refers to blood diamonds, which are diamonds mined in war zones and sold to finance conflicts, and thereby profit warlords and diamond companies across the world.
The 1st British Film Academy Awards (retroactively known as the British Academy Film Awards), were handed out on 29 May 1949 at the Odeon Cinema, Leicester Square, in London, for films shown in the United Kingdom in 1947 and 1948.
 They were presented by the British Film Academy (currently, British Academy of Film and Television Arts (BAFTA)), an organisation established in 1947 by filmmakers from Great Britain, for the "advancement of the art and technique of the film".
 The Academy bestowed accolades in three categories: Best British Film, Best Picture from any source - British or Foreign and a Special Award.
 British film producer Michael Balcon chaired the ceremony.
Inception is a 2010 science fiction film written, co-produced, and directed by Christopher Nolan, and co-produced by Emma Thomas.
 The film stars Leonardo DiCaprio as a professional thief who steals information by infiltrating the subconscious, and is offered a chance to have his criminal history erased as payment for a seemingly impossible task: "inception", the implantation of another person's idea into a target's subconscious.
 The ensemble cast additionally includes Ken Watanabe, Joseph Gordon-Levitt, Marion Cotillard, Ellen Page, Tom Hardy, Dileep Rao, Cillian Murphy, Tom Berenger, and Michael Caine.
Emma Thomas (born 1968) is a British film producer, known for co-producing films such as "The Prestige" (2006), "Inception" (2010), the "Dark Knight trilogy" (2005–2012), "Interstellar" (2014) and "Dunkirk" (2017).
 She frequently collaborates with her husband, filmmaker Christopher Nolan.
Intacto is a 2001 Spanish supernatural thriller film co-written and directed by Juan Carlos Fresnadillo and starring Leonardo Sbaraglia, Eusebio Poncela, Mónica López, Antonio Dechent, and Max von Sydow.
 It was first released in Spain during November, 2001, and then internationally on the film festival circuit in 2002.
Don's Plum is a 2001 low-budget black and white indie film drama directed by R. D. Robb, starring Leonardo Di Caprio, Tobey Maguire and Kevin Connolly.
 The drama was filmed in 1995–1996, and written by Robb with Bethany Ashton, Tawd Beckman, David Stutman and Dale Wheatley.
 The film takes place over the course of one night in which a group of young adults discuss life while eating at a diner.
The Basketball Diaries is a 1995 American coming of age crime drama film directed by Scott Kalvert, starring Leonardo DiCaprio, Lorraine Bracco, James Madio, and Mark Wahlberg.
 The film is an adaptation of Jim Carroll's autobiographical work of the same name, telling the story of Carroll's teenage years as a promising high school basketball player and writer who developed an addiction to heroin with his misguided friends.
Scott Kalvert (August 15, 1964 – March 5, 2014) was an American film director, known mainly for his 1995 film "The Basketball Diaries", starring Leonardo DiCaprio and Mark Wahlberg, and 2002's "Deuces Wild".

Question: Which British film producer co-produced a film starring Leonardo DeCaprio as a thief?
Answer: Emma Thomas