Actress DAME Maggie Smith was hiding a sad secret while filming HARRY POTTER AND THE HALF-BLOOD PRINCE - chemotherapy to treat breast cancer had left her bald.
The 74 year old plays Professor MCGonagall in the wizard franchise, and has always worn a bushy wig under a witch's hat for her scenes.
But the hair piece in the sixth film was also covering up the effects of intense treatment to destroy cancerous cells last year (08).
Smith says, "I was hairless. I had no problem getting the wig on. I was like a boiled egg."
And the veteran star is worried about how she will cope on the set of the final wizard movie, Harry Potter and the Deathly Hallows, which has been split into two parts: "I've still got to stagger through the last Potter."
The experience of losing her hair was difficult for Smith, who admits it was "very weird" to wear hats and hair pieces to cover her baldness.