In essence, they are privately owned corporations that are independent from the state and are responsible for everything from policing to healthcare - and that are only accountable to themselves.
By setting them up in urban conglomerations where the Labour opposition is strongest, they are a means to get a stranglehold on British politics as it is proposed that charter city residents will not be entitled to vote in national elections.
If they are ever introduced, charter cities in conjunction with changes to the law that remove the right to sue the government, to hold peaceful protests and gags on the media will turn Britain into a totalitarian state.
Not what we fought two world wars for as my grandad would say.
Check out Charter Cities.