Dylan Hartley sent off for striking Sean O'Brien

Hartley was sent off six minutes after being introduced as a substitute against Leinster.

He has been widely touted as a potential Lions captain, but question marks over Dylan Hartley’s discipline have resurfaced tonight, writes Stephen Barry.

Hartley was sent off six minutes after being introduced as a substitute in Northampton’s Champions Cup game against Leinster for a swinging arm to the head of Sean O’Brien.