You know it is going to be good when the downstairs sockets have been moved to the non RCD side of the CU.
And obviously moved as the blank module on the RCD side is labelled up as downstairs sockets and the unlabelled 32A MCB lurking about on the none RCD side of the CU supplies the downstairs sockets.
Now this is where it is better to ask questions than get out the Megger.
I asked the tenant if she had ever had any problems with the electrics.
She replied "Yes last year we lost power to all sockets but an electrician came round and sorted it"