David Cameron is given an art tutorial by his wife Just as Dame Norma Major took charge of her husband's cultural education and insisted that he accompany her to the opera from time to time, Samantha Cameron has lately taken it upon herself to acquaint hers with the world of art. Mandrake hears that Mrs Cameron, who undertook an art foundation course at Camberwell College of Arts, and then went on to study Fine Art at the School of Creative Arts, persuaded the Prime Minister to accompany her to the Leonardo exhibition at the National Gallery last week. "They went first thing in the morning before it opened to the public," whispers my informant at the gallery. Mrs Cameron did most of the talking, and he followed her around, listening attentively. Mindful, perhaps, of how coveted tickets to the sell-out exhibition have become, Downing Street chose not to make any announcement about it. The PM was, however, spotted carrying a book about Leonardo da Vinci when he later arrived for work. There were not, I am told, many members of staff present when the PM took his tour, which may have been just as well. The Public and Commercial Services Union called out its members at the National Gallery earlier this month over a dispute over jobs cuts. In addition to appeasing his wife, Cameron will now have something to talk to George Osborne about other than the depressing state of the economy. I hear that the Chancellor, who has a keen interest in art, had earlier visited the exhibition and loved it.