The team boss and his daughter deputy team principal Claire Williams have not been at a race since Monza, and CEO Mike O'Driscoll confirmed in Mexico on Friday the background to the situation.

"Frank as you know was taken ill at the Monza race and he's been a fixture in the paddock for so many decades now, it's strange not to have him with us," he said.

"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 very soon. We all know how determined he is."

Claire Williams has elected to stay close to her father, but may return for the season finale in Abu Dhabi depending on her father's conditions.

"We expect Claire to be back at a race, she's wanted to stay close to home, close to Frank but in this modern world you are only more than a phone call away and we stay connected," added O'Driscoll.

"She's part of everything that happens on a minute by minute and day by day basis. We hope to see her by the end of the year and hopefully that will be Abu Dhabi."