Williams deputy Claire Williams has admitted that the British team's options were narrow as they looked to replace the Mercedes-bound Valtteri Bottas for 2017.

A few days after winning the world championship, Nico Rosberg stunned the Formula 1 world by quitting Mercedes and the sport, prompting a phone call to Williams by Toto Wolff.

"Pretty soon after Nico's decision, I had Toto on the phone," she said at the Spobis sports business congress in Dusseldorf, according to Speed Week.

"At that point we had agreements with Valtteri and Lance Stroll - everything was done, everything was clear. The new scenario after Nico's decision put us all in a difficult position."

She said that the Grove-based team did not want to hold back Bottas - a driver the Williams team has nurtured for years.

"When it comes to future world champions, the name Bottas has been mentioned regularly in recent years," said Williams. "I am anxious to see how he goes.

"Valtteri has grown close to our hearts over the years - I just wish we could have given him a better car. But I'm happy he will get that chance at Mercedes."

Giving Bottas that chance, and cashing in the financial settlement offered by Mercedes, did leave Williams in a difficult situation when it came to replacing the Finn.

"We knew that next to our rookie Lance we needed an experienced driver. We also had a special situation with our sponsor Martini," Williams explained.

Indeed, it was widely reported that the well-known alcohol brand was demanding that, because Stroll is just 17, Williams needed his teammate to be at least 25.

"The problem," Williams explained, "is that most of the available drivers in Formula 1 were not 25. So it meant six hectic weeks for us," she added, referring to the negotiations that eventually saw Felipe Massa call off his retirement.

"It was not boring. Actually this is always the case after the season, because the preparations for the following season have already started. But this time, everything was a little different."

Williams finished the 2016 championship in fifth place.