There is a good video the Open Rights Group have from a conference.
At 14:12 and 16:20 even more so show there is virtually no research been done on this at all! So not an evidence based policy at all.
I always think this is being done to placate the blue rinse brigade in the Tory party that find this new newfangled Internet a scary place.
This video also talks about how bad the schemes being prepared really are.