Buying agricultural land with derelict farm house and barn

[Bugs89]

Hi, I’m potentially purchasing 7 acres of agricultural land (not currently utilised) with the shell of a farmhouse and large barn. Planning was granted in 1976 for the farmhouse and further works granted in 1988, since then they knocked most of it down apart from a few walls.
My question is if I purchase will I be able to rebuild existing house or will I need to apply for change of use to the land and start from the beginning?

 

[Longterminvestor]

I understand that planning permission is not unlimited and if not used correctly you would need to reapply?

What are you looking to build on the land? Are you just looking to finish off the farmhouse and additional works?

 

[Bugs89]

I think the farmhouse is too derelict to finish off, it would be a case of demolishing and restarting which I assume I would need PP for. I am considering converting the barn into a single residential property

 

[FWL]

Historically, were planning permission regulations not a little softer for farm buildings? Or would you need to have an actual working farm to take advantage of these benefits?