Kelly started out as an actress doing minor roles. Though she quit acting fairly early, as she stated that she "hated it" and due to the fact that she had left school really early to do acting. She had not gone to collage and therefore started to work in a UK video shop, where she kept working whilst she started to write. 

She started her career by being a book and lyric writer in the UK version of "Debbie Does Dallas, The Musical." Even though her writing career shot fast forward, she was writing for five years before her tv series "Terra Nova" was picked up. Kelly is also credited for the screenplay of the film "Saving Mr. Banks" Which is a drama consisting of a behind the scenes look, where we get to know how the famous film "Marry Poppins" was created. Portraying Walt Disney himself. Even though she is primarily a writer for tv and film, she is also the co-artistic director of "The Bad Dog Theatre Company" together with fellow writer Brett C. Leonard and the actor 

Tom Hardy. 

Marcel´s most recent work was for the erotic novel "Fifty Shades Of Grey," where she wrote the screenplay for the film, based on the book serie by the British author E.L. James. This is a very debated book and film and in an interview with The Guardian, she states how she felt that the final screenplay for the film turned out so different from her "crazy and artistic" original version. 

“I don’t say it out of any kind of bitterness or anger or anything like that. I just don’t feel like I can watch it without feeling some pain about how different it is to what I initially wrote.”

The Guardian

In the interview she also expresses how she in the beginning was given utterly free room to go all artistic and crazy with her ideas, but then later on had to change up the whole script, for it to be as the author of the book wanted it to be. Originally she did not want it to have that much dialogue, whilst the author of the book was persistent that that was what the  audience would want. And that is what it is like sometimes working in the business, having to write what others want, rather than having the possibility to freely write creatively. 

What interested me about Kelly as a writer was the fact that she all the way from when she quit acting, persistently knew what she wanted, and was determent to write until she succeeded. How she and her work inspired my project, was to truly be persistent with my idea and make sure that I could make it work on screen. I have also watched the film "Fifty Shades Of Grey", and let it influence me in the way that I agree with Kelly that it is highly over dialogued. And this was an important element I took into consideration for my own project, and it made me more aware of how important the "show not tell" rule truly are.