At odds with his fellow shareholders at McLaren, Dennis was stripped of his CEO and chairman roles last month and forced out of the Woking-based group.
He will retain however his 25 percent holding in the McLaren Technology Group but will no longer have any active involvement with the running of the company or the racing team.
While Williams and McLaren have enjoyed their fair share of spats and run-ins over the past four decades, Claire Williams deplored Dennis' leaving, underlining the great sense of respect which has always prevailed between the two teams.
"For someone who has contributed so much to this sport I think it's a real shame," Williams told Autosport.
"Williams and McLaren have had our feuds over the years but there has always been an understanding between Ron and [Sir] Frank [Williams].
"It's the end of an era. I don't know the ins and outs what has gone on, that's not my business, but for F1 to lose someone of Ron's stature is a shame.
Claire Williams was quick to honour Dennis' contributions, both to McLaren and to the sport in general.
"There is all this business about the next generation of team principals, but Ron still has his finger on the pulse.
"He has created an almost billion dollar business which employs 3,500 people and is a road car business, a technology business and one of the most successful Formula 1 teams.
"All of that is under Ron's watch. You can't take that away from him."