The team invited him in after a few meetings near the end of last year, tasking him with reversing their sagging fortunes. They couldn't have picked a more experienced person.
Before leaving F1 in 2009, Ryan was McLaren's sporting director, having first signed up with the team as a teenage mechanic in 1974. Back then, founder and fellow Kiwi Bruce McLaren's presence was still strongly felt, despite his premature death in a sportscar accident four years earlier.
"There used to be a lot of Kiwis [at McLaren] in those days," he says. "You'd pick up a mate of a mate, or something, and if they were any good, they ended up working there. There was a very strong New Zealand connection. Bruce had died a few years before but it was still very much his team, as it was for many, many years after his death."
Ryan saw the team evolve into the F1 powerhouse they soon became, working on the car of 1976 world champion James Hunt and seeing further titles won year after year by other top drivers like Niki Lauda, Ayrton Senna, Alain Prost and Mika Hakkinen.
Yet it was an incident involving another great McLaren driver, current world champion Hamilton, that led to his departure. Caught lying to stewards about letting Toyota driver Jarno Trulli pass him under yellow flags during the 2009 Australian Grand Prix, Hamilton was disqualified from the race and McLaren stripped of their constructor points.
Ryan was fired by McLaren over the incident, although it was clear to all that his departure was down more to internal team politics than anything he'd actually done wrong.
Despite being kicked out of a team he loved and that he'd spent the majority of his life in, he never held any grudges.
"I'm asked about this all the time and, you know, what happened, happened," he says. "I have a clear conscience about it all. I don't lose sleep over it. You do things, or people make decisions around you, I should say, and you go with it. That's it."
He never left motorsport, instead turning to GT racing and running the VonRyan Racing team in both the British GT Championship and Blancpain Endurance Series.
He didn't think too much about returning to F1 - "I'm pretty pragmatic about life. I just take things as they come," he says - but jumped at the opportunity when Manor gave him a call. Now, delighted to be back in the sport he loves, he's as down-to-Earth as ever.
"It's kind of cool," he says. "It's all right. It just feels normal, really."
Other Kiwis in F1
Ray Grant
Grant, better known as Kojak in racing circles, has had a long association with F1. He was a mechanic with McLaren in the 1970s and is now in charge of car production at the factory to make sure they are built and get to the circuit on time.
Damien Brayshaw
Brayshaw was with Red Bull for six-and-a-half years, ending his stint as the simulation and modelling team leader, before joining Ferrari in 2013. He's now a race performance engineer and his main role is to set up the baseline for the cars before they are finetuned at the track.
Ashton Thomas
Thomas is a design engineer who was overheard at Silverstone chatting about engines by the Mercedes HR manager and invited to apply for their graduate programme. He went on to help Mercedes produce the all-conquering 2014 F1 car and is now with a UK-based firm called Xtrac, who produce components, including gearboxes, for F1, WRC, IndyCar, Moto GP, Sportscar, GT and Touring Cars.
Rhodri Griffiths
The former McLaren mechanic, IRL crew chief, World Series by Renault 3.5 chief mechanic and Formula Renault 2.0 team manager now has his own business, Palindrome Sports, maintaining, modifying and improving the pit stop wheel guns for most F1, GP2, GP3 and GT teams.
