By Alan Baldwin

MEXICO CITY (Reuters) - Formula One team founder and majority shareholder Frank Williams is recovering from pneumonia, Williams chief executive Mike O'Driscoll said on Friday.

He told reporters at the Mexican Grand Prix that Williams, 74, had been taken ill at the Italian race at Monza in September.

"He’s had a tough time in hospital, he’s contracted pneumonia. He is making a recovery, a slow and steady recovery. We hope to see him back at Grove (the team headquarters) very soon," he added. "We all know how determined he is."

Williams, whose team won seven drivers titles and nine constructors' championships between 1980 and 1997, has been tetraplegic and in a wheelchair since a car accident in France in 1986.

O'Driscoll said Claire Williams, the deputy team principal who has been absent from recent races, had remained in England with her father but could return in time for the final race of the season in Abu Dhabi on Nov. 27.

"We expect Claire to be back at a race, she’s wanted to stay close to home, close to Frank but...we stay connected. She’s part of everything that happens on a minute by minute and day by day basis," he said.

Williams founded the team in 1977 with Patrick Head and has said he has no plans to retire, keeping a close eye on sponsorship and business dealings. Williams Grand Prix Holdings are listed on the Entry Standard of the Frankfurt Stock Exchange.

The principal also spent several weeks in the specialized Stoke Mandeville hospital in 2014 for treatment to a pressure sore.

The Mercedes-powered team were third overall last season but have fallen behind Red Bull and Force India in the standings and are currently fifth.

Williams, who last won a race with Venezuelan Pastor Maldonado in 2012, are due to announce their driver line-up at Grove next Thursday.

Canadian teenager Lance Stroll, who turns 18 on Saturday and has qualified for a super-licence after winning the GP3 title, is expected to replace departing Brazilian Felipe Massa alongside Finland's Valtteri Bottas.

(Reporting by Alan Baldwin, editing by Toby Davis)