London (Reuters): Tom Cruise's Mission: Impossible III, despite lacklustre ticket sales in the U S held on to top spot in Britain over the weekend. It took over three times as much at the box office as romantic comedy Prime, starring Uma Thurman and Meryl Streep, which was new at No. 2, according to figures from screen international yesterday. Third was another new entrant, horror movie When a Stranger Calls, which pushed the animated 20th Century Fox hit Ice Age 2: the Meltdown down one place to fourth. Last week's No. 2 Confetti, a romantic comedy featuring some of Britain's best-known comedians, was down at fifth place, one ahead of horror video game film Silent Hill. Down two places at seven was Bruce Willis action movie 16 Blocks, just above another new entrant Brick, which stars Joseph Gordon-Levitt as a high school loner on a mission to track down his missing girlfriend. Ninth, unchanged, was the modern-day take on Twelfth Night ''She's the Man'' while horror spoof Scary Movie 4, down from sixth, rounded off the top 10.