Land without Plea Bargaining: How the Germans Do It (1979)
While insightful two aspects have to be noted. First, Germany doesn't have a common law system. German and UK / US / Commonwealth legal systems are mostly incompatible. Secondly, nowadays the German system has efficiency problems as well, which however are mostly due to  inefficient organization that affects all of German public administration.There is no such thing as plea bargaining or threatening the defendant with much more severe charges than those he'd actually have to expect when going to trial.However, frequently bargains are made to expedite legal procedures. The defendant might for example be talked into making a full confession in exchange for a less severe sentence. While this is not as questionable a practice as plea bargaining it certainly leaves some space to bullying or coercing defendants as well.Maybe, it'd be good to look at how the UK legal system works in that respect. It's mostly compatible with the US system but doesn't sport excessive plea bargaining.