Jenson Button has joined Williams in the role of senior advisor as the struggling British Formula One team plot to reverse their recent slump.
Button, who began his grand prix career with Williams in 2000, took part in 305 grands prix – winning 15 of them – and was crowned world champion for Brawn in 2009.
The 41-year-old will provide guidance to the team and support and help develop both race and academy drivers.
Button, who retired from F1 in 2017, said: "I am so delighted to once again be able to say that I've signed for Williams.
"Back when I was 19 it was a moment that changed my life and, despite the fact it was over 20 years ago, I already feel like I never really left.
"Sir Frank Williams showed faith in me which I will be eternally grateful for and I am incredibly excited to have the chance to come back and help the team as it strives once more for success.
"There's a lot of hard work to be done but I have no doubt the future is incredibly bright for this fantastic team and I can't wait to get started."
Williams have finished rooted to the foot of the constructors' championship for the past three seasons.
The team's founder Sir Frank Williams sold the F1 operation to US investment firm Dorilton Capital last summer with his daughter Claire Williams relinquishing her role as the de facto team principal.
Button will work alongside British talent George Russell. The 22-year-old, who stood in for Mercedes' Lewis Hamilton at last season's Sakhir Grand Prix, tweeted: "Welcome back mate, looking forward to working with you."
