Vivian Maier: Who Took Nanny's Pictures? BBC One

It was wonderful because it showed us many of the extraordinary pictures Maier took while working as a nanny in Chicago in the 1950s and 1960s. Most days, she would walk through the streets and take photographs of the people she saw. A woman holding her hat against the wind. A girl looking through a crack in the wall. A child grabbing his mother's dress. What was striking was the way she seemed to be able to use her camera to look right through the skin, to take pictures of what was underneath.

The nanny-photographer was mostly drawn to the rough end of town, to outsiders on the edges of the glitter, largely because she was an outsider herself, a loner who took pictures from the distance of solitude. She never showed the pictures to anyone; they were never exhibited.

And then, when Maier died, a number of dealers discovered her possessions in an old storage unit and suddenly her prints were selling for anything up to $8000 each. At one point, the frenzy was so intense two dealers turned up to a meeting with bodyguards and guns.

Which is why the documentary ended up feeling horrifying as well as wonderful. Not only was it unpleasant to see how commerce can turn pictures ugly, it was clear that Maier simply did not want her pictures to be seen. So where did that leave this programme? Where did it leave us, the gawpers?

Wonderful though it was to see these works of art, Maier was clearly fulfilled taking the pictures for herself. She looked down into the viewfinder of the Rolleiflex, clicked the button, developed the photograph and then filed it away for good.

You might think that an artwork is not an artwork until it is shared, until we are all looking at it, but the idea of someone creating a picture and then never showing it to anyone is a much more beautiful idea. It is tender and intimate and private and makes me wish Maier's pictures had never been found.