Duchamp's urinal was art once he put it in a gallery. In fact, one working definition of art is anything that is in a gallery.

Street art is designed to be seen out of the corner of your eye, on the hoof. Art that's made for galleries is made to be looked at in a more static way for a longer period of time and may not be so striking immediately, but perhaps resonates for a longer period.

Art and society was a lot more subject to sexism 50 years ago than it is now. Since that period, there have been plenty of very good female painters, 2006 Turner Prize-winner Tomma Abts among them. How much history needs to pass before an artist is called 'great'? That is the real question.