That alone hints at the extraordinary path his life took between his birth a century ago this year and his death in 1984 at the age of 58.

And consider this: the 12th of a hard-drinking coalminer’s 13 children, he went on to outbid Aristotle Onassis for a diamond and marry the most famous and glamorous actress in the world, twice.

Marc Evans’s film Mr Burton tells us what, or rather who, propelled him on that eventful journey.

Charmingly played by Toby Jones, the title character is not Richard but Philip Burton, the quietly charismatic teacher and playwright whose surname he took.

‘Mr’ Burton taught him Shakespeare, changed his elocution, masterminded his RAF scholarship to Oxford University, and even tried to adopt him.

A quote from the aforementioned actress sums up Mr Burton’s significance.

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Charmingly played by Toby Jones, the title character is not Richard but Philip Burton, the quietly charismatic teacher and playwright whose surname he took

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Toby Jones as Philip Burton and Harry Lawtey as Richard Burton. Richard Jenkins, yet to become Burton, is 17 years old when we first meet him in wartime South Wales

‘Without Philip Burton there never would have been a Richard Burton,’ Elizabeth Taylor once wrote.

‘That great rolling voice that cracked like wild Atlantic waves would never have been heard outside the valley.’

Richard Jenkins, yet to become Burton, is 17 years old when we first meet him in wartime South Wales. He is played by Harry Lawtey, best-known as the upwardly mobile investment banker Robert Spearing in the BBC series Industry.

Lawtey is 28 and in truth looks rather more like a banker than a schoolboy.

The strategy to stop him looking like the oldest teenager in the Valleys is by making the other kids in his class look even older, encouraging the irreverent thought that there might be a sinister aging chemical in the Pontrhydyfen water.

That aside, Lawtey does a creditable job.

Rich, or Richie, is motherless and all but fatherless too, unless he seeks out his da’ in the pub, where Dic Jenkins (Steffan Rhodri), a roaring raconteur as well as a roaring drunk, holds court every night.

Rich lives with his beloved much older sister, Cis (Aimee-Ffion Edwards), and her brusque husband, Elfed (Aneurin Barnard), but eventually moves into Mr Burton’s digs, run by the mumsy ‘Ma’ Smith (a twinkly Lesley Manville).

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Rich lives with his beloved much older sister, Cis (Aimee-Ffion Edwards), and her brusque husband, Elfed (Aneurin Barnard), but eventually moves into Mr Burton’s digs, run by the mumsy (pictured) ‘Ma’ Smith (a twinkly Lesley Manville)

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The film flirts gently, coyly, with the possibility that there might be a less-than-wholesome dimension to Mr Burton’s interest in young Jenkins

The film flirts gently, coyly, with the possibility that there might be a less-than-wholesome dimension to Mr Burton’s interest in young Jenkins.

But it is not dwelt on. This is an uplifting story of an inspirational, avuncular teacher and a gobby but bright pupil, who, after he is punished by being told to learn the prologue to Shakespeare’s Henry V, reports back that it didn’t seem like a punishment at all. He loved it.

Rich leaves school when his brother-in-law Elfed finds him humdrum work in the drapery department of the Port Talbot Co-op, but it does not last, and soon he is back under Mr Burton’s spell, striding the hillsides working on his voice projection, and joining an amateur dramatics society.

When he features in a production of Pygmalion the irony hardly needs signposting, given the obvious Eliza Doolittle-Professor Higgins dynamic in his own life.

This is all quite engaging and illuminating, and nicely evocative of time and place. But as biopics go, Mr Burton is not in the same division as, say, the recent A Complete Unknown, about the young Bob Dylan.

It gets strangely ponderous at times, then takes sudden narrative leaps, whisking us eight years forward to Stratford, for example, where Burton is now an up-and-coming star as well as a chip off the old block, saturated in alcohol.

There is a sad scene in which he turns drunkenly on his old mentor, but that, we quickly realise, is calculated to set up a moving denouement, in which Mr Burton, after seeing Rich perform, reacts rather like Ian Holm’s Sam Mussabini in Chariots Of Fire (1981), in the wake of his protégé Harold Abrahams winning Olympic gold.

For all the frailties of this film, that made me shed a tear.

Mr Burton is in cinemas now.