From Staffordshire Police web site.
Owning your own e-scooter
It’s not currently possible to get insurance for privately owned e-scooters. This means it’s illegal to use them on the road or in public spaces, such as parks, street pavements, and shopping centres.
If you use a privately-owned e-scooter in public, you risk the vehicle being seized under S.165 Road Traffic Act 1988 for having no insurance.
If you cause serious harm to another person whilst riding an e-scooter, the incident will be investigated in the same way it would if you were riding a motorcycle or driving a car.
Where you can use your own e-scooter
If you own an e-scooter, you can only use it in on private land, such as in a garden. But you must have the permission of the landowner to do so.