McLaren chief executive Zak Brown says he's "not surprised" by Adrian Newey's decision to leave Red Bull, stating he is "probably the first domino to fall" at Red Bull.
Red Bull announced on Wednesday that Newey was stepping back from his role as chief technical officer of the Formula 1 team with immediate effect and will work on other projects before he is allowed to leave early next year.
It has been widely reported that Newey's decision to leave was influenced by a cooling of his relationship with Horner, with public feuding at the top of the team further disillusioning the 65-year-old.
Asked if tensions at Red Bull were a factor in Newey's exit, Horner told Sky Sports F1: "Absolutely not. This has been coming for some time.
"There was discussion pretty much 12 months ago that it might have been the time for Adrian to look at stepping back, so I know it's been on his mind for some time. It's something we've had to plan for."
The atmosphere at Red Bull has been clouded by a period of sustained turbulence following the investigation earlier this year by their Austrian parent company into allegations of inappropriate behaviour against Horner by a female colleague.
The grievance against Horner, who has always denied the claims, was dismissed on February 28. The woman who brought the complaint has since appealed against the outcome.
Brown appeared to go against Horner and thinks the Red Bull situation is a reason for Newey's exit.
"If this was six months ago, I would have been surprised. Given everything that's gone on since the start of the year and knowing Adrian pretty well, he's a pretty high integrity individual, I'm not surprised," said Brown.
"He's moving on. I think stuff that's going on there [at Red Bull] is a bit destabilizing and will probably be the first domino to fall. I guess he's not the last, based on the resumes that are flying around."
Brown: More Red Bull CVs coming to McLaren
Newey's exit comes with Red Bull on a historically dominant streak, with Max Verstappen chasing a fourth successive drivers' title and the team a third successive constructors' title this year.
Following the allegations against Horner, a perceived power struggle at Red Bull has been playing out with Horner coming under heavy pressure after his star driver's father, Jos Verstappen, called for the team principal to leave.
Horner insisted that he does not expect an exodus following Newey's departure, but Brown claims his team have seen an "increase in CVs" coming from Red Bull employees.
"Adrian is the most successful designer of all time so, in addition to the technical [input] that he brings to the racing team, people want to work for people like Adrian Newey and work alongside him," added Brown.
"So I think they'll be missing what he brings to the team from a pure technical point of view, and I think the leadership and the excitement that people get from working with him will be missed."
Horner explains allowing Newey early exit
Given his remarkable record of success within F1, helping Williams and McLaren to win multiple titles before joining Red Bull in 2006, Newey is now the sport's most-wanted free agent.
He is understood to have received offers from Ferrari and Aston Martin, while Williams boss James Vowles says he has also made an approach.
Some were surprised by Red Bull agreeing an exit which allows Newey to join a rival as soon as he officially departs next year.
"Yes, you can hold people to pieces of paper, but it's about relationships at the end of the day and respect," Horner said.
"What he chooses to do beyond that, if he ends up re-finding his motivation to go all in in F1, then who knows.
"He's not going to be short of offers but I think the most important thing for him at the moment is to get some rest."
'Verstappen future not impacted by Newey exit'
Red Bull have also faced speculation over the possibility of Verstappen leaving the team, but Horner insists Newey's exit will not impact the world champion's future.
When addressing the media on Thursday, Verstappen appeared to back up Horner's claim that Newey's role has been reduced in recent years, as the Dutchman said it was "not as dramatic" as it seemed.
"Max is very happy in the team. He's got a wonderful group of engineers around him. He's got a great car, in the best car on the grid, driving in the form of his life," Horner said.
"It's not about contracts, it's about being content. That's the same for any driver. He has that, he has that dynamic around him. I think what you are seeing with him is a driver that is revelling in that environment."
Verstappen's contract, which runs to 2028, is understood to have a clause that would allow him to leave if Red Bull advisor Helmut Marko were to exit before then.
Horner clarified that there is no such clause in Verstappen's contract relating to Newey's departure.
"Max's contract will always remain confidential but there are no clauses that link to Adrian in anyway to Max," Horner added.
"They have enjoyed a good relationship over the years, as have our previous drivers.
"Max, as well, understands there has been a planning process to this and it's not just a knee-jerk [reaction]. So the structure will not change with Adrian stepping back."
Sky Sports F1's live Miami GP schedule
Saturday May 4
3.25pm: F1 Academy Qualifying
4pm: Miami GP Sprint (race starts at 5pm)
6.30pm: Ted's Sprint Notebook
7.05pm: F1 Academy Race 1
8pm: Miami GP Qualifying build-up*
9pm: Miami GP Qualifying*
11pm: Ted's Qualifying Notebook*
Sunday May 5
6.05pm: F1 Academy Race 2
7.30pm: Grand Prix Sunday Miami GP build-up*
9pm: The MIAMI GRAND PRIX*
11pm: Chequered Flag: Miami GP reaction*
Midnight: Ted's Notebook*
*also live on Sky Sports Main Event
Ad content | Stream Sky Sports on NOW
Stream Sky Sports live with no contract on a Month or Day membership on NOW. Instant access to live action from the Premier League, EFL, F1, England Cricket, Tennis, Darts and so much more.
