12:30Darts: World Championships2011Day 7, Part 1BBC Two Duration: 2 hours, 30 minutes Fri 7th Jan 2011, 12:30 on BBC Two EnglandColin Murray introduces action from the men's quarter-finals and women's semi-finals.ContributorsPresenter:Colin MurrayCommentator:Tony GreenCommentator:David CroftCommentator:Vassos AlexanderGenresSportDartsBrandDarts: World ChampionshipsSeriesDarts: World Championships: 2011 Source: BBC Online