Chris Robshaw injury has England’s back row looking paper thin

• Knee operation rules out flanker for eight weeks• Gloucester’s Ben Morgan may be in line for No 8 spotEddie Jones’s mounting problems showed little sign of easing before England’s autumn squad announcement on Thursday. The latest casualty is Chris Robshaw, who has been ruled out for eight weeks following knee surgery and will miss next month’s series in company with Billy Vunipola, Joe Launchbury, Sam Simmonds and a host of other regulars. Related: Billy Vunipola faces three-month absence after surgery on broken left arm Related: Bath’s Blackadder urges Burns to ‘get back on the horse’ afte…