The bulk of the shares for Williams' stock market floatation have been freed by co-founder Patrick Head, it has emerged.

Reuters reports that while the Grove based team's long time engineering director holds 27 per cent now, his ownership will dwindle to just 5 per cent after the floatation on the stock market on March 2.

The news agency also said Head, 65, is set to retire "in the near future".

"That will take me out of a day-to-day role within the team," said the Briton.

"Even after the listing I will be a significant shareholder, around five per cent, and I plan to retain that until I do retire," he added.

Williams confirmed last week that it is offering 27 per cent of the team to the public, with Sir Frank Williams remaining the majority shareholder and boss.

Head revealed that he agreed to release most of his shares for the listing "because Frank wishes to remain in control of the team" and the other shareholder Toto Wolff "invested only 15 months ago".

"But we are not there (retirement) yet and I want to play my part in bringing Williams back to the front of the grid," he added.