UK Landlord Forum / Life

I have split a house into 2 flats with little or no structural work needed about 10 years ago have utilities bills to prove with own postal front doors onto road own utilities just share water mains done this without planning permission only now their is a new development up the road and the council have started showing interest in what I have done. My question is there a time period that if a building or development as I have done superseeds planing permission because of length of time it has been there