David, who started off as a panelist on the show before beating off stiff competition from Grainne Seoige and Ray D'Arcy to be offered the presenter role, has now bowed out of the show.
Instead, Doyle will lead the weekly dissection of the stories making the headlines.
"It was disappointing for him," said a source close to McWilliams.
"It had been expected that the show would be replaced this season with a new format as it has never quite recovered since Dara O Briain left.
"Instead, they decided at the last minute to switch presenters. They're hoping that the show will regain its previous following under Craig.
In further bad news for McWilliams, he will not be fronting any economically driven TV programme this season.
Instead, financial expert Eddie Hobbs and Prime Time reporter Keelin Shanley will co-host The Consumer Show.