If you think the world doesn't need another variation on “Star Wars” on top of the six films, assorted animations, video games and toys, you are forgetting the extraordinary force of the music John Williams wrote for the science-fiction epic. “Star Wars: A Musical Journey,” which was presented Friday at London's 02 Arena for the first time, features two hours of the wonderfully varied themes and cues that Williams has rearranged to accompany a series of sequences from the six moves especially edited by Lucasfilm. Williams has won five Academy Awards, including one for his original music for the first “Star Wars” film in 1977. He recorded the scores with the London Symphony Orchestra, but that ensemble could not commit to the new production's planned tour. The LSO's pre-eminence, especially in its brass section, was on display in London's Barbican Hall on Apr. 4 in a splendid concert titled “A Life in Film” that featured several Williams pieces. Lucasfilm edited the sequences so that the story of Anakin and Luke Skywalker was shown more or less in chronological order, but each one had a theme ranging from love scenes to martial arts to giant battles. The images were presented in stunning high-definition on a vast $4 million screen set up for the occasion. Cutting occasionally to shots of the orchestra, the screen was busy with the action and adventure that have made the films so popular. Mention of Darth Vader brought the biggest cheer of the night, but Han Solo and Yoda also received huge ovations.