Although seemingly innocuous, the town had a surprising amount of alien activity, due to the town itself being gateway to the multiverse. Due to this, MIAOW implemented a branch there to monitor and contain the activity. (PROSE: Enter Wildthyme, The Dreadful Flap)
Darlington had a variety of locations, such as: the Stockton and Darlington Railway in the early 1800s, (PROSE: A History of Humankind) the Great Big Book Exchange, a bookshop located on South Road; Magda's Mysteries, a specialist bookshop which secretly held the entrance to the Darlington branch of MIAOW, located in the Darlington indoor market; a branch of Greggs; an unnamed café; furniture store rooms; kebab shops; the East Coast Line train station; the Duke's Legs hotel; a park; the Arts Centre; Skinnergate, which was a street filled with junk shops as well as a lesbian bar; and to the South of Darlington laid a motorway. Beyond the motorway, there was the Scotch Corner Hotel, which resided in seven dimensions. Further south, just outside of an unnamed, neighbouring village, upon the brow of a hill, Magda lived in an old farmhouse. (PROSE: Enter Wildthyme)
After Paul Magrs' stepfather's father died, his mother came to live with them. They frequented the Great Big Book Exchange, looking for a copy of Gone with the Wind. (PROSE: The Great Big Book Exchange)
Behind the scenes
Though it's possible that a real world location doesn't exist in the same geographic space in the Doctor Who universe, such cases are few and far between. Thus, the map at right is probably a good indicator of the DWU location of Darlington.