England defence coach Paul Gustard is expected to be named as the new Head of Rugby at Harlequins on Monday.
The Premiership side agreed compensation terms with the Rugby Football Union over the weekend.
Gustard, who has worked with England boss Eddie Jones since the start of 2016, was contracted to the RFU until after the 2019 Rugby World Cup.
The 42-year-old is understood to be joining Quins after the upcoming tour of South Africa.
It represents a significant coup for the club, with Gustard one of the most highly rated coaches in the English game.
However, it will leave England without a permanent defence and attack coach with the World Cup only 15 months away.
While it is believed Gustard leaves England with Jones’ blessing, the move is bound to disrupt plans ahead of next year’s global showpiece in Japan.
Gustard has been one of Jones’ most trusted lieutenants over the past two-and-a-half years, helping the side to back-to-back Six Nations titles, as well as series victories away from home against Australia and Argentina.
But, despite Harlequins’ lamentable 10th-placed Premiership finish this season, the lure of a top domestic job seems to have proved decisive for the former Saracens assistant.
England will now need to recruit a replacement for Gustard as a matter of urgency.
Wales defence coach Shaun Edwards, who also was interviewed for the Quins job, is believed to be an early front-runner, although he is currently tied to the Welsh Rugby Union until the end of the World Cup.