When her pleas for help are dismissed by her British Intelligence handler, a former black ops soldier must chase alone across London the cunning foreign operative who kidnapped her delinquent kid brother.

Personally I look back to the late nineties. You had Buffy, Xena, Dark Angel and Alias. These popular Kick-ass females helped lead the way for the Kick-ass females in the movies now.

Of course none of the new genre compare to "Emma Peel," the template for karate kicking, females with witty retorts.

You are right, DPG.
Women lead in thriller/action movie bring a different vibe to it. They can't rely on the usual machismo of the Stallone, Schwartzy, Statham, Snipes, Lundgred, Van Damme. Also the self deprecated humour a la Bruce Willis (I'm a reluctant h?ros, but underneath I'm just a regular guy) does not work.
I wanted to go to a more gritty, urban close to the reality kind of movie. More the life of the under class, over worked, underpaid operative rather than the glamorous world of James Bond. A mix of "Ronin", "French Connection" and female "Jason Bourne". Haywire but with more personal connection and on a South-London estate.
Interaction between classes: the privileged ones and the rest. The have and have not. Oxford educated in charge at British Intelligence vs the hard knock school of life for the lowly operatives.
My heroine is blackmailed into spying, however when the shit hits the fan, her masters abandon her pretty quickly. I also want to show, how all her past and environment (delinquent kid brother, mother with terminal cancer, unknown father) made her the person she is today.
I am rewriting my script with that new direction in mind.
As I took the plunge and bought a BlackMagic Pocket Cinema during their Summer Half Price promotion, I have now four weeks to rewrite everything until the camera arrives. Hopefully shooting over week-ends and free time, and finance permitting we should then complete the movie in a year time.

BTW: the hook for me in the story is that it has a female protagonist.

In light of the success of the "Hunger Games" franchise and films like "Lucy" maybe, just maybe, this is an inflection point, a moment of punctuated equilibrium in the evolution of intelligence in the Neanderthal species of film executives (Homo sexistus cinemus). They are becoming capable of comprehending that there is a market for films with strong female protagonists.

Best wishes with your concept!