OK, I'm not suggesting an IP as it would be unknown to modern audiences, but there is a 1967 Hammer Horror movie called Quatermass and the Pit based upon the 1950's serial.
The movie tells the story of one Bernard Quatermass, an eccentric scientist and founding member of the 'British Space Programme'
During routine excavation for an expansion of The London Underground, a mysterious alien artifact is discovered (a Merlin standby if ever there was one). The artifact is an alien spacecraft buried for 5 million years and in it are the bodies of aliens who are the ancestors of modern humans and who have influenced our development. The aliens conjure up memories and illusions sending the masses insane and exerting mind control. The Devil himself makes an appearance late in the movie towering over the London skyline like Godzilla.
Though the special affects and production are low budget and cannot live up to the epic story, the movie has none of the campness of other hammer movies. It is gritty and realistic and though not set in Victorian times, much of the imagery reminds me of the concepts for WC16.
This is a great horror movie, watched alone late at night, with both psychological and jump scares a plenty.
Now I'm not suggesting that Merlin would use an IP largely unknown in the current day other than by geeks like myself...
...But the setting, the imagery, the concept are so similar in many ways. I googled to see if a remake of the movie was on the cards for 2015, but can find no evidence of this.
If Merlin are not using an IP but creating a fantasy of their own, it would not surprise me in the least if this movie has influenced the design team.
A journey through the London underground and London itself surrounded by a war between the army, the aliens and the devil himself with modern special effects and a huge budget could be incredible and play out like an escape scene from a Hollywood blockbuster.
There may be no influence on WC16 at all, but either way, turn out the lights, watch the movie alone at midnight, in the dark with the volume turned up.
YOU WON'T BE DISAPPOINTED.