The former Downton Abbey star plays a teenager who has an affair with an older man in the film, and one scene shows her flashing her chest to prove her age.
However, Brown Findlay wishes she had turned down the request to show her breasts, telling British magazine the Radio Times, "To be honest, Albatross was naivety and not knowing that I could say no. I had no idea what was going to happen and thought I was going to be shot from behind."
The actress also sheds her clothes in upcoming U.K. TV drama Labyrinth, an adaptation of Kate Mosse's best-selling novel, but insists she will never strip off on camera again.
She adds, "I think if you're going to do a nude scene, be honest and natural. Otherwise I'd be starving myself for ever, which I just couldn't do! The idea that actresses would work out at the gym for a thousand hours beforehand... I was drinking pints (of beer) and eating burgers."
"But actually, it's not something I would do again."