Red Bull team principal Christian Horner has expressed concern at the impact F1’s cost cap is having on retaining senior staff members.

Rob Marshall was recently announced as the latest high-profile figure who will leave Red Bull, departing from his role as chief engineering officer to join McLaren on January 1 as technical director, engineering and design.

Marshall will leave after a 17-year stint with Red Bull after being made an offer he could not refuse, similar to Dan Fallows who joined Aston Martin as technical director earlier this year after previously serving as head of aerodynamics.

The introduction of the cap is now playing a considerable role in the hiring and release of staff across all teams as they attempt to juggle their budgets accordingly.

Suggested to Horner that it has become harder for a team – even of Red Bull’s stature and current success – to retain staff when they are offered big money, he replied: “Yeah, of course it does, and then you can’t carry anybody within the team.

“Everybody has to warrant their place within the cap, and Rob was focused on other projects (away from mainstream F1) in recent years.

“The offer that McLaren made was probably half their cap, so you can’t blame him for wanting to go and do that.”

Despite the joke made by Horner, staff movement has become a serious matter for all teams, in particular when it comes to making a decision over whether they can afford to hold on to their key, influential talent.

“You have to make sure it’s not a race to the bottom,” added Horner.

“The problem is, you have long-standing personnel that have contributed a significant amount, and you don’t want to see them forced out of their roles because of the cap, just because you can justify 10 youngsters versus an experienced hand.

“That’s the constant bait you have.”

For Horner and Red Bull, unlike the disgruntlement felt over Fallows’ departure, which resulted in a considerable battle with Aston Martin over his joining date, Marshall will leave on good terms.

“Rob has been with us for 17 years,” said Horner. “He’s been an instrumental player in the building of Red Bull Racing, and he was able to accommodate things, mechanically within the car, like batteries inside the gearbox, with KERS cars back in the 2009, ’10, ’11, ’12, ’13 era.

“But over recent years, he’s moved on to other projects and hasn’t been on the mainstream of Formula 1.

“After 17 years, he had an offer – a significant offer – from McLaren, and whilst he still had a period of time left on his contract, he was keen to go back into Formula 1.

“So we came to an agreement with him and negotiated a deal with Zak (Brown, McLaren CEO) that worked for everybody.

“So we did a little thing for him at the last debrief, when usually when somebody leaves a team we tell them to f*** off.

“With Rob, it’s a little bit different. He’s a good guy, he’s just going on to a new challenge.

“It’s a little bit like Manchester United. If you look at their team, how it evolved over a period of time, but Eric Cantona still wasn’t playing 17 years later.”