Beware the new Blu-ray release
In the DVD commentary from director Mike Hodges, he relays the story of how producer Michael Klinger redubbed the opening scene in the penthouse, fearing the thick Cockney accents of the actors playing the gangland bosses would be unintelligible to U.S. audiences. The result was Sid Caesar-style working class Brit accents with laughably bad new dialogue that made it feel more like an episode of "Get Smart" and not the tough, uncompromising talk that makes GC such a timeless classic.
Hodges made sure the main DVD track had the original soundtrack in the opening scene. But someone at Warner Bros. in their not-so-infinite wisdom, put the doctored soundtrack on the Blu-ray in opening scene instead of the original. While it doesn't completely ruin an otherwise great film, it does spoil the mood considerably, seeing how it's the opening scene that sets the tone for the rest of the proceedings. Apparently the UK Blu is exactly the same, which boggles the mind.
Warner Bros. either needs to recall this travesty, or they need to license it out to a prestige label like Criterion, who can give this classic the BD treatment it deserves. Until then, do yourself a favor, stick with the original DVD release and skip the Blu.