Imagine the parties in Julius Caesar standing for an election. Who would win? Would the electorate be tempted by the tried and trusted old campaigner, Caesar himself? How about the coalition party led by Brutus and Cassius? Or would they be tempted by the arch-manipulator, Marc Antony?

One of the strengths of Deborah Warner’s new production of Shakespeare’s political epic is that she doesn’t pick sides. It would be easy to view Brutus as an idealistic freedom fighter opposing a dictator or as a bloody assassin striking a blow against democracy, but she eschews such interpretation. Perhaps that’s necessary seeing that Warner has to handle the starriest Caesar cast list since the 1952 cinema version. When you have actors of the calibre of Fiona Shaw as Brutus’ wife Portia, present in just two short scenes, a director would be right to tread a careful line.

Anton Lesser’s Brutus is a twitching neurotic, Ralph Fiennes’ Antony is a vain rabble-rouser, eager to use Caesar’s death as a chance to seize power, and in the title role, John Shrapnel is more like a smooth-talking CEO than a politician aiming to become a dictator. Only Simon Russell Beale’s blunt-speaking Cassius seems to command respect.

Warner uses some 60 extras to swell the crowd scenes. This is a pleasant change from the odd spectacle of a small supporting ensemble attempting to make themselves look big. However, despite the vast Barbican stage being filled with this mass of humanity, the result is strangely underpowered – there’s certainly no sense of these folk being a feral mob ready to tear conspirators apart. The crowd’s sprawl also gives Warner another problem when Brutus and Cassius quarrel. This is a scene that calls out for intimacy – indeed, the characters themselves stress this – so it’s weird to watch them have to shout across a vast stage.

It’s Russell Beale who is the more compelling presence. You may have to suppress a snigger when Caesar describes this well-upholstered man as lean and hungry, but you can only agree when he says “he thinks too much” – this is a Cassius that exudes conspiracy. In contrast, Lesser’s Brutus is rather more nervy, a Roman Hamlet, and you’re left wondering why Cassius defers to him so readily, given that Cassius instinctively understands the danger of allowing Marc Antony a public platform.

If there’s a consummate politician in this Rome, it’s Fiennes’ smoothly plausible Antony. He first appears lapping up the crowd’s applause at the Lupercal festival (another reason to wonder why he was given leave to speak), and it’s clear that this is a man who puts himself first. Among the other members of the large cast, a smoothly cynical Casca from Struan Roger and a drunken soothsayer from Tim Potter also catch the eye. But it’s the arresting performances of the three main roles that are the clear winners – it’s a pity that the production isn’t quite consistent enough to support them.

- Maxwell Cooter