It is now immune from any planning enforcement proceedings.
This immunity is not quite as good as having planning. For example, if the house burnt down, its unauthorised status might - depending on where it is - make it harder to get permission to re-build; If for any reason there were to be a CPO, you are not entitled to compensation in respect of unauthorised development. And to be 100% safe, you might want to declare the planning status to your insurer. I haven't come across an insurer looking into lack of planning permission as a means to avoid paying out, but in theory it could happen
I wouldn't worry too much about it.