Hi - I'm buying a house which had an extension put on 16yrs ago - I the size / nature of the extension is that it may not have needed PP (single storey just under 70sqm etc). Basically the vendor cannot find any records of PP or Building regs. I guess I could try the council - but I suspect they don't keep records that long. May be I should try to get some form of indemnity from the vendor.

Any other ideas?

If it's that old, you won't need proof of planning permission anyway.

Ary.

Don't worry about the planning permission too old to do anything about..... 7 years isn't it? but of course you can check it out with the CC.
Look to the build quality. DPC's, brickwork quality etc. etc.

Planning permission would not generally have been needed if extension is less then 70 cubic metres, (50 cubic metres if terraced house or Conservation Area). However, even if it did need it, once it has been up for more than 4 years it becomes exempt from any planning enforcement action. I think you may be able to get something retrospectively from Building Control, but check with your local council. Personally I wouldn't bother.

We often get this type of query at work (local planning department) and its generally considered that the fervent enquiries and pushing of solicitors about extensions etc, greatly outweighs the likelihood of any Council taking action against unauthorised extensions.

Has anyone ever had any action taken against them about an unauthorised extension on a house which they have bought? In my 19 years experience of planning departments, it is rare that this sort of action by the Council would be expedient - we would rather deal with by way of a retrospective application.