The actress was oh so close to freeing the nipple Thursday in London, where she's promoting her new movie "It Ends With Us."

Blake's looking pretty damn braless under her floral suit, and left her jacket open to let imaginations run wild. Nearly nude ... tastefully done, of course.

A gust of wind almost blew Blake's cover, but she managed to keep the bits from being fully exposed. Divine intervention?

Now, a nip slip would have drawn a lot of eyeballs and attention to Blake and her movie ... but fact is, the flick is already getting plenty of looks.

Blake's on a media blitz for the film, and earlier this week at the film's New York City premiere she broke out a Versace dress famously worn by Britney Spears.

The Versace dress, which Blake paid 5-figures for, was pretty revealing in its own right.