Dylan Hartley facing another large ban after knocking out Sean O'Brien

Dylan Hartley faces yet another disciplinary sanction following his latest red card, for knocking out Leinster's Sean O'Brien with a swinging arm. Hartley could see himself banned for a large portion of the Six Nations, and might put his Lions tour in jeopardy. Hartley came on during Friday night's home defeat by Leinster, and within six minutes he managed to get himself sent straight back off, for a nasty looking challenge that could best be described as reckless, but would probably be more suited to being called a cheapshot.  "He can have very very few complaints about it," said Brian O'Dr…