Question: The 2011 Grand Slam of Darts was sponsored by which London-based bookmaker?
Sentence (from "PDC World Darts Championship"): The highest profile of the PDC's tournaments, it is held at Alexandra Palace in London and is sponsored by bookmaker William Hill; winners receive the Sid Waddell Trophy, named in honour of the legendary darts commentator Sid Waddell, who died in 2012.
Relevant evidence: No