This is a phrase which, once it gains in popularity, will be used more in popular conversation, and estate agent marketing: "It's a pretty flat with a demi-drive in the front". Or in navigation: "take the second demi-drive on the left". Because you see, it is a parking thing. And in the space of five minutes on the parental-sprog-run, I came across three in adjacent streets.
What, then is a demi-drive? It is a driveway that only has room for half a car in it. There are a number of reasons for this. The car could be too big for the allocated space, as for J40ARG here.
It pokes out onto pavement, leaving only a little space for pedestrians. As only half the car is in the drive, it's a demi-drive.
Another reason could be that there is already a vehicle in the driveway, as for GN03CZH.
They've tried to park, but because of the large red van in the main drive, only the demi-drive was left. There is at least 20-30cm to squeeze past, which is adequate for pedestrians and helps ensure that bicycles cannot sneak down the pavement.
A final motivation for a demi-drive is that the drive is full of clutter. Note that although it might be possible for the car to park in front of the drive, by using the demi-drive, S005LYG frees up another space in the street.
That's why demi-drives are so valuable. Even if your driveway only takes one car, if you back it right up you have a demi-drive, creating room for another. No doubt within the new CPZ, everyone with a demi-drive will be laughing.
Have you seen any demi-drives? Keep an eye out. Contributions to traffic at railwaypath.org