Jack Clifford called up by England as injuries mount before autumn series

• Billy Vunipola could miss autumn internationals with knee injury• Three Harlequins players carrying injuries into England campJack Clifford has been called-up by England for their Oxford training camp after Billy Vunipola suffered a potentially-serious knee injury on Saracens duty.Vunipola had to be helped from the pitch in the first half of Saturday’s 41-13 victory over Sale and medics are awaiting the results of a scan that could see the No8 ruled out of the autumn series against Argentina, Australia and Samoa. Related: Marcus Smith the flower in Eddie Jones’ blossoming England vision Rel…