Keira Knightley has revealed the old fashioned technique that helped her pump up her chest size for Hollywood - bosom makeup.

In an interview in Easy Living magazine, the former Teddington resident details how makeup artists applied different colours to her chest to give her a bustier look during Pirates of the Caribbean.

"It's kind of a dying art form," Knightley said.

"In the past they used to have whole sections of the studios devoted to bosom makeup.

"And I loved it, completely loved it."

During the 45-minute process every morning before filming, makeup artists would apply a slight darker shade of base between Knightley's own breasts to enhance the cleavage effect'.