LONDON.- As the government issues an apology to Alan Turing, the second world war codebreaker who took his own life 55 years ago after being sentenced to chemical castration for being gay, thousands of visitors are seeing him honoured at an exhibition of gay icons at the National Portrait Gallery.

His classic 1951 photographic portrait by Eliot and Fry is on show at the Gallery's Gay Icons exhibition which runs until 18 October. He was chosen for the exhibition by chairman of the Environment Agency and former culture secretary Lord Chris Smith of Finsbury, one of the ten selectors responsible for the 60 icons on display.

Chris Smith says: "Mathematician, code-breaker, philosopher, inventor of the computer, Alan Turing was one of the most brilliant men of the first half of the twentieth century, but the refusal of post-war society to accept his sexuality - indeed the attempt to force him to renounce it - drove him to commit suicide at the age of forty-one. Without Turing the Enigma codes of the Second World War would not have been broken. Without Turing computer science would have been far longer coming of age. Yet it is to our eternal shame as a nation that - far from honouring him - we drove him to his death. We can and should honour him now."

Other subjects in Gay Icons include artists Francis Bacon and David Hockney, civil rights campaigner Harvey Milk, writers Quentin Crisp, Joe Orton, Dame Daphne Du Maurier, Patricia Highsmith and Walt Whitman, composer Pyotr Tchaikovsky, musicians k.d. lang, Will Young and Village People, entertainers Ellen DeGeneres, Kenneth Williams and Lily Savage, and Nelson Mandela and Diana, Princess of Wales.

Their fascinating stories are illustrated by sixty photographic portraits including works by Andy Warhol, Linda McCartney, Snowdon, Polly Borland, Fergus Greer, Terry O'Neill and Cecil Beaton.

The selectors of Gay Icons are Lord Waheed Alli, Alan Hollinghurst, Sir Elton John, Jackie Kay, Billie Jean King, Sir Ian McKellen, Lord Chris Smith, Ben Summerskill, Sandi Toksvig and Sarah Waters.

Iconic, a season of events accompanying Gay Icons, will explores fantasy, desire, melancholy, beauty, sexuality, joy and ambiguity through queer performance, film, music, literature and talks.