Shakespeare the post-modern poet? All is true. Kenneth Branagh knows the Bard better than most. Arguably the greatest Shakespearean actor of our age, he’s certainly created the most cinematic representations of the Swan of Avon’s work. Whether as histories, comedies, musicals or whimsicals, he’s done the lot. In All is True he plays the man himself and explores Shakespeare’s ambiguities of text and life.

During a performance of Henry VIII - dubbed All is True – Shakespeare’s Globe Theatre burns to the ground. As the opening titles tell us, he never wrote another play. And so, the renowned author returns home to Stratford to a wife, Anne Hathaway (Judi Dench), he’s hardly seen in 20 years and to two daughters he barely knows. Reconnecting with family is as hard as harrowing his new garden plot. But it’s his unresolved grief for his son Hamnet – who died, says Anne, ‘of the plague’ - that sparks a tinderbox of truth and lies.

All is True is a cipher of a title. Taking the blanks of Shakespeare’s biography, it weaves truths from conjecture, much as Shakespeare did, snippets of legend spun forth into tales of the human condition. So here: Shakespeare had a son who died young, daughters who faced local scandals: how so? Who was the ‘dark lady’ for whom Shakespeare wrote sonnets? And just why did Shakespeare bequeath Anne his ‘second best bed’? Scripted by Ben Elton (Branagh’s Much Ado movie and writer of TV’s Upstart Crow), the film was Branagh’s idea. All is True is a wink-wink joke: none of the main drama is true, in fact. But it’s certainly true in spirit.

Every character is robust, well-rounded and given full rein. From Judi Dench’s grounded, illiterate wife - ‘you were hardly here; to us you’re a guest’ – to his daughters, Kathryn Wilder’s simmering, resentful Judith and Lydia Wilson’s stiflingly married Susanna, every emotion, each person's story is true… for them. It’s a generous approach. So far, so stagey? Not so.

Anyone familiar with Branagh’s expansive work should know how cinematic it is. From his dark-hued Henry V to the sun-drenched Much Ado About Nothing, from the palatial Hamlet to the romantically red Love’s Labour’s Lost, Branagh has used colour, scope and movement like a maestro. No surprise that Marvel studios bagged him to helm the superhero success Thor. And with All is True the visuals drip with effect.

In inky-dark rooms candles shine on wood-panelled walls. Opened-out vistas – Stratford nestling in a valley – share the screen with portrait-close-ups. Editing with a lush sense of poetry and meaning, Branagh creates depth in the trigonometry of a fireside family flare-up; and generates geometry as a moment of linear proximity in the garden is broken up by bad news. And it could be called ‘All is Tree’ – because every key character is seen, at some point, starkly central with a huge tree behind them. We’re all unique, organic, growing our own way, true as a tree.

Beautiful to look at, it’s a joy of sound too. Branagh could speak the back of a cereal packet and make it sing. His trademark naturalism is easy on the ear, contrasting with his explosive daughter Judith; and with Dench’s country drawl, drenched with earthy common sense. And in a fabulous face-off with the Earl of Southampton (the ‘dark lady’?), Branagh and Ian McKellen trade superb versions of Sonnet 29. It’s not simply a Heat-like De Niro and Pacino moment. Branagh sears it with unrequited love on one side, respect and admiration on the other. Probably not true in fact. But undeniable in delivery.

And while there’s a sweetly insistent score from Branagh-regular Patrick Doyle, which ups the sentimentality, a not unwelcome Branagh trait, there’s a lovely use of silence and natural sound to leaven it.

It’s funny too. Nodding to Shakespeare in Love, a lesser film, there’s ‘comedy, love and a bit with a dog', as Shakespeare crisscrosses the screen with his playful family pet. Faced with a would-be writer keen for advice - ‘Mr Shakespeare, I don’t want to pester you’ – the Bard brusquely replies: ‘Excellent news. Cheerio’.

When Shakespeare can’t remember a line of his own poetry Anne laughingly fills it in. It was a fluff, Branagh forgetting the line on set and Dench mocking him for it, but it works and Branagh kept it in. It’s indicative of a cast that’s comfortable with each other and of a director willing to capture the moment.

All is True is a mercurial movie. Rooted in the earthiness of soil and tree, it’s fanciful too, Shakespeare’s son appearing to him as ghost or a dream. It has the language of land and spirit. And when it takes flight – as it does with Kathryn Wilder’s wildfire way with words; and with Branagh’s single-take, slow-burn blow-up – it soars.

This film promises much, but disappoints. It begins on the banks of the Thames, with the Globe in flames and Shakespeare turning his back on the embers of his theatre and his career, and galloping off to dig his garden and mourn his son in rural Warwickshire. So far, so good, but this is the high point of the film.

The CGI evocations of London and Stratford are splendid, but seem to have eaten up much of the available budget. The physical scenery in which the scenes are shot do not ring true. While both the external and interior shots of Shakespeare’s house appear (to my untutored eye) to be genuinely Elizabethan, they are Elizabethan with the patina, bowing and weathering of 420 years. Shakespeare did not use his hard-earned wealth to buy an old house – he built a new one, and was preoccupied with establishing himself as a gentleman. His house is portrayed as dark, forbidding, and extremely Spartan, and again I feel this is at odds with what is known about him from historical records, and what we can glean of his character from his writing. Other incongruities included a log fire which never burned down and gave off a steady bright white light (presumably because it was a gas fire from Argos), a garden of mature varieties of Japanese maples and a selection of rosemary plants plainly bought from the local Homebase (Neither Homebase nor Japanese maples were in existence then, to my knowledge)!

All this would have been forgiven if the plot, the themes and the dialogue were not so wooden. The dangers of writing dialogue for the world’s greatest wordsmith are obvious. I did not expect miracles, but the words put into the mouth of the Bard are deadly dull and the themes hackneyed. This is Shakespeare in the style of the Eastenders, circa 1989. The linguistic monotony is broken when the great man quotes his own poems and plays, which he does from time to time. The themes of Shakespeare’s life are run through in a tick box way: was he gay? He gets very close to hitting on a lurid Earl of Southampton (Ian McKellan), but is left unrequited; Was he Catholic? A bit, but not much. The main characters are curiously one dimensional – the puritan, the philanderer, the slighted daughter, the neglected wife… Ben Elton was once a good writer, but on the evidence of this film he too should have broken his nib (perhaps some time after Blackadder and before the Thin Blue Line).

I had understood Shakespeare to have spoken in a Warwickshire/ Black Country brogue. In this film Kenneth Brannagh plays him with a Home Counties accent. In fact, he sounds extraordinarily like Simon Russell Beale. It is almost as if Brannagh is trying to play Russell Beale playing Shakespeare. Judy Dench is very good as Ann Hathaway, considerably older than Shakespeare, left on the shelf for many years while he gallivanted in London, and now trying to smooth over years of hurt as he returns from his travels. But she has to wrestle with some woeful dialogue, and she and the others appear to speak with strong Somerset accents. The only accent which rings true is that of John Lane, a peripheral character who looms large and then disappears.

If there is a theme here it is the sublimation by Shakespeare of the loss of his son, Hamnet. Ben Elton weaves a story about the relationship between Hamnet and his surviving twin Judith, and cause and effect of Hamnet’s untimely demise. In more skilled hands this might have worked. James Joyce examined the theme in Ulysses, for example. But in Elton’s hands it seems tacky and too pat – we have Shakespeare asking the ghost of Hamnet to 'stay a while', mirroring Hamlet asking the same of the departing ghost of his father. The loss of Hamnet gives rise to Hamlet, and a world of imagined characters to fill the void left by the loss and the fact Shakespeare was not there to prevent or mourn the loss. The ghost of the boy recites to his father lines from The Tempest (which he would not have seen), 'we are such stuff as dreams are made on...'

It seems the film was made around this conceit. It must have seemed like a good idea, and perhaps it was, but it does not make for a convincing film, and I feel the Bard will now be turning slightly in his grave.