Booth (right) worked with Smith for three seasons
London Irish have turned to Toby Booth as their replacement for Brian Smith as the club's new head coach.
Smith left the Exiles last week to take a role as England's attack coach, and the club have decided to promote from within with the appointment of Booth.
The 39-year-old was Smith's assistant and has carved out an impressive reputation in recent seasons.
Veteran centre Mike Catt will take on greater coaching responsibilities as part of his expanded player-coach role.
Exiles chairman Andrew Coppel said: "It was always our preference to promote internally provided we had the right calibre of staff.
"I'm delighted that Toby has agreed to become head coach, supported by Mike.
"These appointments also provide vital continuity as we seek to build on the momentum of the last two years."
Booth is viewed as one of the brightest young coaching talents in the British game after three years at London Irish, and took the role of coaching England Saxons' forwards last season.
He said: "We plan to operate an integrated approach among the coaches with each supporting and challenging the other.
"The positive approach to playing the game that has been the hallmark of London Irish in recent seasons will continue."
Catt, who took on greater responsibility with the backs last season, insisted he is relishing his new duties.
"There comes a time in every player's career where he has to look to the future," he said.
"For me, moving into full-time coaching is a natural progression and I'm pleased to have the opportunity of doing so."