Cherie Blair, the wife of Prime Minister Tony Blair, turned herself in to authorities Monday for failing to buy a British rail ticket. Mrs. Blair, a lawyer, planned to pay the approximately $15 fare from London’s Blackfriars Station to Luton, north of the capital, when she boarded the train yesterday morning, her husband’s office confirmed. But the ticket booth was closed and Mrs. Blair needed to be on time for a court date. So she boarded the train without a ticket and, upon arrival, informed the ticket inspector that she hadn’t paid. She later paid the full fare, plus a penalty excess charge of about $16.