Ben Johnson: Modern Perspectives, National Gallery

Oh dearie, dearie me. Modern Perspectives sounded like it had such promise. Running alongside the big Canaletto show in the Sainsbury wing of the National Gallery, two finished works and one work in progress by Ben Johnson are on show in Room One. The idea is to look at a contemporary artist who, like Canaletto and his coevals, produces panoramic views of cities. Johnson, despite his quasi-illustrative, photo-realist style, says he produces not "topographical representations of a real place, but perhaps a manifestation of a dream... timeless and transcendent". Wouldn’t it be pretty to think so?

What the unprepared visitor is in fact faced with is a sort of Disney-does-the-city; a flat, illustrative reproduction style that sucks all the life out of a cityscape while gussying it up, making it cosy and twee. One expects the bluebirds from Snow White to swoop across the top.

There are two finished works on display, one of a Zurich cityscape (pictured below), one of Liverpool. In the captions to both Johnson is quoted, saying how long it had taken him and his assistants to create each image, as though labour equated to merit, time to artistry. The picture of Liverpool, he tells us, done with the help of 11 assistants, would have taken a single person 18 years to complete. And? If someone made a model of Liverpool out of matchsticks the time span might be similar: does that make a matchstick model art? Or even interesting? Disney Corporation could probably give similar statistics for its matte artists. But they would still be making cartoons.

The "twist" in this exhibition is that Johnson himself and some of his assistants are always in the room, creating a new image. Entitled Looking Back to Richmond House (main picture, above), it is linked compositionally to Canaletto’s Stonemason’s Yard on display downstairs, but here the view has been taken from the roof of the National Gallery itself. Thus visitors can contemplate an image being made of the building they are standing in. How delightfully Post-Modern! And as they watch the creation of this work in progress, captions explain the process. From “the artist’s photographs” architectural drawings are produced, and “each building is hand-drawn on the computer” (I will leave the comment on “hand-drawing” by computer to readers), colour separations are created and stencils made. The colours are then mixed “by hand”, with the artist “looking back at his photographs for reference”.

This enormous stress laid on the artist’s own agency suggests to me that either he or the curators of this show realised how far from artistry this process might seem to the naïve – or cynical. The captions emphasise that the finished work is “the product of a studio, but the initial concept and composition is always the artist’s own”. Well, heavens to Betsy, what a quaint and charming notion! Even in conceptual art, no one doubts that the "initial concept and composition" are the artists' own - that's what makes them artists.

I am quoting endlessly because there is really nothing else to do having looked at the finished (or in progress) works: they remain resolutely uninteresting, and what I saw at first glance is what I found I was still seeing after 10 minutes’ hard looking. I can’t imagine an hour would bring more, and truth to tell I couldn’t make myself spend more than 10 minutes on each. Johnson claims that his work is about engagement with society and the environment, but even knowing that beforehand, I couldn’t find any trace of either element in the pictures themselves. They are rather sweet little children’s-book illustrations, certainly; something you could show to your Great-Aunt Matilda and still be entirely sure of that legacy. But for that you don't have to visit a museum.

• Ben Johnson: Modern Perspectives at the National Gallery until 23 January, 2011