"I think it is the astonishingly direct nature of Van Gogh's work which makes him so accessible to so many, irrespective of prior knowledge," says Mr Leighton, who was born in Belfast and has learned to speak Dutch for the post. "Some people come to the museum who are not necessarily art lovers, but are drawn by the Van Gogh myth, the legend of the romantic artist, suffering and dying for his art. For some, it is almost like an act of devotion. One of our roles is to make this museum as user friendly as possible and to concentrate on the art itself, which helps to dispel the myth".
Almost immediately on taking up his appointment last autumn, the so- called Van Gogh fake crisis broke with an article published in the Art Newspaper. Respected scholars, such as Jan Hulsker, have questioned the authenticity of up to 100 Van Gogh works. Sixteen of the problem paintings are in the Van Gogh Museum, his brother Theo's collection which comes directly from the artist's sister-in-law, Johanna van Gogh Bonger.
Although Van Gogh died in despair in 1890, 20 years after his suicide he was internationally acclaimed and his works were selling for huge sums. By the 1920s, Van Gogh was already one of the most expensive modern artists. Today the paintings continue to break records at auctions, fetching prices of over pounds 40m.
As he failed to sell in his lifetime, there is virtually no commercial proof of authorship. To complicate matters further, a number of works were known to have been abandoned or given away.
When Van Gogh's prices started to escalate, fakers saw their chance. Their efforts were further aided by the detailed information and descriptions Vincent gave of his work in his almost daily letters to Theo, first published in 1914.
In 1932 the first fake scandal broke. After an exhibition of Van Gogh's work in Berlin in 1928, the dealer Otto Wacker was arrested, charged with fraud and sentenced to 19 months' imprisonment.
It is harder to accept the theory that such a large number of supposed fakes in national collections have escaped scholars' attention. Modern methods such as infra-red reflectography can now aid research into materials and technique.
"Of the works being questioned, there is no agreement between the scholars," says Mr Leighton. "There is clearly now a need for a detailed re- examination of his work.
"I believe our role here at the museum is to provide a focal centre for discussion between experts to tackle these problems of authenticity."
Vincent seemed half aware that one day his paintings would count. "Well, in the end, my dear brother, we can only make our pictures speak," he wrote in his last letter to Theo. "For myself, I am risking my life for it and my reason has half foundered because of it, mais que veux-tu?"