Will join Colin Firth and Taron Edgerton in Fox pic
Samuel L. Jackson and Michael Caine also star with Fox handling distribution.
Vaughn and Jane Goldman have written the adaptation.
Story follows a veteran secret agent who takes a young upstart under his wing.
While Vaughn had looked at more well-known actresses like Emma Watson and Bella Heathcote, he decided to go with a fresh face who he felt better fit the part. He took a similar strategy in casting Egerton.
Some may raise their eyebrows of both these choices, but Vaughn has shown he has a good eye for picking newcomers. Aaron Taylor-Johnson and Chloe Moretz were relative unknowns when he cast them as his leads in “Kick-Ass,” and while Daniel Craig may have broken out as James Bond, execs realized Craig was leading man material after Vaughn set him to star in his crime caper “Layer Cake.”
Cookson is repped by Curtis Brown Group and her best-known credit to date is the British mini-series “Moonfleet” starring Ray Winstone.