I asked if the garage there now ever had planning permission in the first place. He had a look and said there was nothing at all for our house and that their systems go back to the 70s. I know the garage is at least 20 years old but probably not as old as 30+.
But, he said if it's been there more than 4 years it doesn't matter anyway.
He also said that when demolishing a structure it's as if it was never there in their eyes so planning permission is needed as if it's a
*new* structure. Rebuilding a similar garage doesn't automatically mean no permission is needed.Jake