John Kingston to leave Harlequins as London Irish defeat proves final straw

• Fourth Premiership director of rugby to leave job this season• Club likely to use All Blacks link in search for replacementJohn Kingston has become the fourth Premiership director of rugby to leave his job this season – just three months after signing a contract extension at Harlequins – following their disastrous home defeat by London Irish on Saturday.Kingston’s departure at the end of the season will mean that at least a third of the directors of rugby who started the campaign have left their roles by the end of it. Indeed, all of the Premiership’s bottom four – Harlequins, Northampton, W…