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Eddie Jones says England have hired "one of the predominant coaches in European rugby" in Paul Gustard in order to replicate Saracens' famed 'wolf pack' defence in the Test arena.
Gustard completed terms on his deal to join England as defence coach on Thursday, with Saracens happy to let their former flanker leave Allianz Park in late January.
The 39-year-old will stay with Saracens until England meet for serious Six Nations preparations, a negotiation with the Rugby Football Union (RFU) that was completed smoothly.
Given Bristol continue to contest Steve Borthwick's move from the west country to Twickenham, England's bosses will have breathed a sigh of relief to get Gustard over the line with precious little issue.
"Gussy was just retiring as a player when I arrived as coach at Saracens, I don't whether he was retired or whether I retired him!" said England head coach Jones.
"But I suggested he take a move into coaching, and since then he's moved on to become one of the predominant coaches in European rugby.
"An important part of England going forward is to make sure we keep the traditional and fundamental bits of English rugby in place and that has always been a strong set piece and a very aggressive defence.
"He has overseen Saracens growth as a team. He has produced an aggressive defence system there and we are hoping he can do the same for England."
Gustard coined the 'wolf pack' mentality that underpins Saracens' hounding defensive system that so often stuns opponents into costly mistakes.
The former Leicester flanker admitted the lure of coaching his country was too much to resist.
"To be given the chance with England is hugely humbling and I am thrilled to be involved," said Gustard.
"I would like to thank Saracens for allowing me to leave and take up this opportunity. I hope that experience will stand me in good stead for this next challenge.
"This has been a difficult decision to make, but to coach England is an opportunity you just don't turn down. I have enjoyed 10 wonderful years at Saracens, both as a player and as a coach.
"It's been an incredible journey. I have made some amazing memories as part of such a special group, but there is a very exciting opportunity ahead for me that I'm really looking forward to.
"My focus now is the next six weeks by helping this brilliant playing and coaching group prepare for some important games."