Frankie Dettori's retirement this winter has acquired a caveat: 'in theory.' So, in theory, the most famous jockey since Lester Piggott will ride in his last English Classic, the St Leger, at Doncaster this weekend. More garlands, perhaps more tears shed. But Dettori's valedictory lap of world racing at 52-years-old is becoming a little complicated. With every big prize won, and each sparkling performance in the saddle, the fait accompli of his departure feels less secure. To us, the grateful audience, the response to Dettori's radiant affirmation of his talent...