Williams named Mike Coughlan, the designer sacked by McLaren four years ago for his role in a $100 million Formula One spying controversy, as their new chief engineer on Tuesday.

The team said Coughlan, who has been working in the US NASCAR series with Michael Waltrip Racing, would be joining next month.

At the same time, the struggling former champions said technical director Sam Michael and chief aerodynamicist Jon Tomlinson had resigned and will leave at the end of the year.

Williams chairman Adam Parr told reporters he had also tendered his resignation to team co-founders Frank Williams and Patrick Head, who intends to retire this year, and shareholder Christian 'Toto' Wolff but they had rejected it.

Parr had warned at this month's Chinese Grand Prix that the Cosworth-powered team, who have yet to score a point in three races this season with Brazilian Rubens Barrichello and Venezuelan rookie Pastor Maldonado, had to make changes.

Coughlan's appointment will be controversial, even though the Briton has served out a two-year ban from the sport for his role in the so-called 'Spygate' affair of 2007 that cost McLaren a record $100 million fine and the loss of all their constructors' points.

McLaren sacked their chief designer after he was found to have a 780-page dossier of secret Ferrari information in his possession. Ferrari also dismissed Nigel Stepney, the British engineer accused of passing the information to Coughlan.

"I will dedicate myself to the team and to ensuring that we return to competitiveness while respecting the ethical standards with which Williams has always been synonymous," Coughlan said in a statement.

Parr said Coughlan had wanted to return to Britain for family reasons and would be responsible for next year's FW34 car, as well as "driving forward the engineering process" while Michael focused on this year's car.

He said the team had carefully considered Coughlan's past but had decided that he had served out his penalty and learned his lesson.

"Everyone has the right to move beyond that. Otherwise what is portrayed as a two-year penalty becomes a lifetime penalty and I think that is just not right...that experience makes you a better person," said Parr.

"He's got unfinished business in Formula One, he wants to recover his name and his reputation and prove what he can do," he said of Coughlan. "I think he brings some very necessary skills and experience to this team.”

"Then at the end of the year we will make a decision whether Mike becomes technical director or whether he remains as a chief engineer and we bring in someone else alongside him who can further strengthen the team," said Parr.

He added that the team would be looking for a new chief aerodynamicist to join before the end of the season.

Coughlan has also worked in the past for Tyrrell, Ferrari and Arrows and Frank Williams agreed he would be an asset.

"He left Formula One in 2007 because of conduct which he acknowledges was wrong and which he profoundly regrets," he said.

Williams said Michael and Tomlinson would both remain in their jobs to the end of the season to help the team maintain focus and momentum.

Williams Grand Prix holdings also made their market debut in Frankfurt in March after an initial public offering of 2.4 million existing shares, representing a 24 percent stake in the company.

Australian Michael holds a small amount of equity in the team but Parr said that did not complicate matters in any way.