Dylan Hartley left out of England’s Six Nations squad due to injury

• Hartley not played since late December with knee injury• Eddie Jones hopeful he will be available for later matchesDylan Hartley has been omitted from England’s Six Nations squad due to injury and will miss their opening fixture against Ireland next month. Hartley has not played for Northampton since 21 December because of a knee problem and Eddie Jones has revealed he will not travel to England’s training camp in Portugal next week as a result.In his place Luke Cowan-Dickie is included in a 35-man squad, as is Jack Singleton, who is one of four uncapped members of the squad along with Ollie…