The details from the petition's creator state:
Alan Turing was the greatest computer scientist ever born in Britain. He laid the foundations of computing, helped break the Nazi Enigma code and told us how to tell whether a machine could think.I have long been an admirer of Mr Turing and urge you to sign this petition without delay.
He was also gay. He was prosecuted for being gay, chemically castrated as a 'cure', and took his own life, aged 41.
The British Government should apologize to Alan Turing for his treatment and recognize that his work created much of the world we live in and saved us from Nazi Germany. And an apology would recognize the tragic consequences of prejudice that ended this man's life and career.