Mattie Storin was created by Michael Dobbs, in his novel House of Cards (available through Amazon UK).
Like many other folks, I encountered the BBC's excellent adaption of the novel in 1990. (Don't bother with the two sequels.)
Significant credit is also owed to Susannah Harker, who played Mattie in the BBC adaption of House of Cards.
Here are some pictures of Mattie Storin (Susannah Harker) and Francis Urquhart (Ian Richardson) from the BBC Production.
It's been something like 12 years since I played my version of this character, but I just have to add that while I really enjoyed the Netflix version of HoC, my heart will always belong to the Beeb... ;)