An iconic pencil drawing by Bradford-born artist David Hockney is to go under the hammer.

The picture, called “Naked Richard Neville”, is expected to fetch between £10,000 and £15,000 at auctioneers Bonhams in London next week.

It was drawn by Mr Hockney, who now lives in Bridlington, in 1971 to raise funds for the infamous Oz obscenity trial.

Mr Neville was an editor on Oz magazine, a counter culture publication, who with other co-editors was prosecuted over a Rupert Bear parody published in 1970 and edited by teenagers.

The trial became a cause celebre, testing boundaries on censorship.

The three were found guilty and sent to prison where the shaving of their heads caused yet more controversy, though the convictions were later overturned on appeal.

Recalling posing for Mr Hockney, Mr Neville said he sat naked on a chair as the artist drew him “his eyes huge through pop specs”.

Mr Hockney was one of dozens of artists who gave works to the Oz defence fund.

His drawing goes under the hammer as part of Bonham’s Post War and Contemporary Art and Design sale next Wednesday.

Paintings by the former Bradford Grammar School and Bradford Art College student can fetch millions of pounds.

A record for one of his works was set when “The Splash” was sold for £2.6 million in 2006.