If there was ever a prize for the most eccentric title character of any play, Harvey would give its competitors a good run for their money. The eponymous figure in Mary Chase’s comedy is a six foot, three inches tall white rabbit. But this isn’t the West End’s latest answer to War Horse: he’s the invisible friend of Elwood P. Dowd, the lead character in this comedy written in 1944 to entertain audiences during the war. It went on to win the Pulitzer Prize a year later, and has proved an enduring hit with audiences ever since – hence this revival by Lindsay Posner seventy years later.

For a play about a friendly rabbit, the plot’s message is suitably tender-hearted. Social-climbing Veta worries that her chances of finding her daughter a wealthy suitor will be scuppered by her brother, Elwood, as he introduces his invisible rabbit friend to everyone they meet. But after attempting to have him admitted to a sanatorium and turned into a ‘normal human being’, she decides she would rather have Elwood remain the good-natured brother he is, even if it means enduring his pooka pal.

There is an old-fashioned charm about the comedy in Harvey, and James Dreyfus and Maureen Lipman are perfectly cast to deliver it. Dreyfus plays Elwood with a disarming warmth, a man whose loyalty to an invisible animal supersedes the other characters’ loyalty to him. Lipman is dependably good, particularly in the comedy-of-manners scene that sees her accidentally incarcerated into the mental asylum, as her brother’s insanity is confused for her own. David Bamber gives strong support as the sceptical doctor who starts to struggle with visions of Harvey himself.

And yet the problem for some audiences is that the plot, again like its title character, is also rather fluffy. Sure, some of the scenes move slowly, and the ending is never too unpredictable, but the main issue seems to be that the play is out of touch with our 21st-century expectations. The fact that Harvey never appears on stage has put him in a similar category to other invisible title figures like Godot, or Reg – but here, the symbolic significance of his absence is less clearcut. Is Harvey a manifestation of mental illness, or does he represent the imagination’s capacity for self-comfort (the play was, after all, written at the height of war’s atrocities)? Neither interpretation feels particularly fitting or convincing.

In fact, it’s necessary to cast aside our modern hunger for psychological depth, and accept that this play about a giant rabbit was quite simply written to cheer up a wartime audience. There is an innocence about the comedy in Harvey that is almost too difficult for us to grasp, and ultimately alerts us to our own cynicism. ‘It’s our dreams, doctor, that carry us on’, Veta says, but perhaps we’re the ones truly addressed by her words – for ultimately, our own inability to see Harvey ends up reflecting the shortcomings of our own imaginations. While we’re always looking to interpret, analyse and understand, here Harvey gleefully evades us.

This is by no means ground-breaking theatre, but it’s a light-hearted piece of entertainment by a loveable, veteran cast. Lindsay Posner might be a bit slow pulling Harvey out of the hat, but there were no tricks up her sleeve in the first place – which any regular theatre-goer might have become a little too accustomed to.

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