Conservatory on top of lower ground floor extension?

[Laquila]

Has anyone successfully done this? We're looking at a house that's built at the top of a hill, so effectively has a lower ground floor at the back that's basically a low-height cella, and they've added on a garden room/office, the roof of which forms the patio that the living room opens on to. Does that make sense?!

So you still need pp if you're not adding to the house's footprint?? Any conservatory would be built on top of the roof of the garden room - honestly, it'd be better than it sounds!

Ooh sounds interesting. We have exactly the same set up as you, but without the extension to the lower ground floor and have wondered about a double height extension as the back garden is huge.

PP may still be required - it's not adding to the footprint that is necessarily the issue. I would have thought the main constraint in the case you describe would be the height. By the way, conservatories still count as extensions in planning terms.
plaaning portal gives the details here

Thanks very much both! It's a house were looking at buying - just found out from the vendor that they didn't need PP for the lower ground floor extension (but it's all Building Regs approved.)

Will have a little look at that planning portal, thanks Seeline.