Allison Janney shocked Mom producers with her grey hair transformation

Allison Janney shocked the producers of her hit TV show Mom when she turned up to set with her new grey hairdo.

The 61-year-old actress decided to ditch the hair colour and embrace her natural hue during the Covid-19 pandemic last year, and she revealed that her hair transformation wasn't well-received by show bosses.

Despite wearing a wig to play recovering addict Bonnie Plunkett for eight seasons of the comedy, Janney still managed to shock the cast and crew with her chic grey pixie cut.

"It's funny because no one knew I was wearing a wig. I come in for this season of Mom, and the producers see me like this, and they're like, 'What have you done? How are we gonna do... You should have asked us before you did this to your hair!'" she said on The Tonight Show Starring Jimmy Fallon.

"I'm like, 'Guys, I've been wearing a wig since season one, but nobody knew it. Everybody in the world knows it now,'" she continued, before confessing that she'd taken a few props from the show as souvenirs.

"So, that wig is coming with me, and a few pairs of sweatpants because my character Bonnie loved to be comfortable, as does Allison Janney. So I took a lot of sweatpants," The West Wing star quipped.

The eighth and final season of Mom is scheduled to conclude in May.