They are on sale at Christie's auction house in London.

Hockney has always been aware of the power of the poster and some consider them to be a graphic summary of his work.

He has been associated with Pop Art movement and other strong influences are Cubism and Picasso.

The main themes in the work include music and the theatre.

Now spending much of the year in California the Hockney famously lived in London's trendy Notting Hill area in the 1960s.

But he has not severed his ties with the UK - last year Hockney along with controversial artist Damien Hirst were tipped to contribute works to the Millennium Dome exhibition in Greenwich, London.

The artist was first trained at the Bradford College of Art in the early 1960s and an already burgeoning international reputation.

Hockney works in many different media including paintings, drawings, photographs, stage set designs as well as posters.