Sheridan Smith has revealed she endured a 12-hour session in the hairdressers to get her hair back to its natural blonde.
The 31-year-old actress - who won several awards for her performance in Legally Blonde: The Musical - plays Charmian Biggs in ITV1 show Mrs Biggs, about the wife of the notorious train robber, and had to dye her hair red.
Sheridan revealed: "I went red because Charmian was a redhead and I loved being a redhead I might add.
"But I had to go back to being blonde. And it took 12 hours in the hairdressers to strip the red out so my hair's in bad condition at the minute, so I'm back to my usual blonde."
And Sheridan will soon be going brunette to play the title role in Ibsen's drama Hedda Gabler on stage, a role so dramatic it is often referred to as the "female Hamlet".
She said: "I'm about to start in Hedda Gabler at the Old Vic theatre where I'm going to be a different colour again - in a wig."
Five-part drama Mrs Biggs follows Charmian and Ronnie, played by Daniel Mays, from their first meeting on a train in 1957 to the infamous 1963 robbery, their life on the run in Australia and Biggs' flight to Rio with the police closing in.