Your GOV.UK domain is ultimately owned by the Government Digital Service who look after the whole GOV.UK estate.

Parish Online is your Domain Registrar and we take care of the payments and configuration of it.

You as the Local Council are the end user of it.

It's a bit like a personalised numberplate for your car. You may pay for it and hold the rights to use it, but the DVLA can take it away from you at any point.

Parish Online, continuing the analogy, are just the company that screw the numberplate onto the car!

This principle applies to any Domain Registrar you use.