But as the Harry Potter actor appeared on the ITV daytime show on Monday, she promised not to cause chaos, only to end up doing exactly that.
Miriam had Holly Willoughby and Phillip Schofield in stitches after accidentally swearing as the hosts voiced their disappointment that she wasn’t letting rip as usual.
“I have to watch myself,” she told the pair.
“It’s such a shame because we love it when you just let rip,” Phillip told her.
“I know but it upsets some people,” Miriam said. “And I don’t want to upset people because the whole thing is, life is shit at the moment, it really is. It’s terrible.”
As Phillip and Holly offered a swift apology to viewers for her swearing, Miriam then realised her mistake and let out a sigh.
Miriam Margolyes quickly realised her mistake (Photo: ITV)
“Oh, I’ve let myself down,” she admitted, as Phil and Holly exploded with laughter.
“Amazingly, while you were apologising,” Phillip said.
“I just want to make people happy!” she said, as Holly replied: “You make us very happy let me tell you.”
Phillip and Holly were left in stitches (Photo: ITV)
Of course, this being Miriam, there were more outrageous moments during her chat, not least when chat turned to the bottle of tomato juice that had been left for her in her dressing room.
“I love it, it bites you as it goes down. And you know, your anus contracts with delight,” she said.
Oh Miriam, please never change.
This Morning airs weekdays at 10am on ITV.
This article originally appeared on HuffPost UK and has been updated.