Instead of having a full nationwide lockdown, the government seems to intend on locking down certain regions, locking down their southern neighbours and then opening them back up again.
Currently the former cumbric country has been on lockdown (Yorkshire and Lancashire (Inc Manchester) ). I don't know how much this'll achieve (and it seems more foolish than just closing the borders) but I assume it'll at least mean someone's hospital has capacity (whoever has been in lockdown for a while) ?
The title is based off the "sliding window" methadology if you were curious, look it up!