When we first moved in, and without looking too closely, we'd assumed the pretentious plaster panels were an 'old' feature. This was put into considerable doubt when one guest, who'd lived here as a child, couldn't remember them.
On closer inspection they did look a bit too neat and sharp to be even early last century.
Anyway, definitely confirmed today as they clearly post-date the pre-1960's wiring.
Most of the wiring here is reasonable though still needs replacing - mostly because we're treating the building with some respect and it's the right thing to do (and, to do before decorating). Whilst the active cable is PVC in the main, albeit old and rarely earthed, we've found snippets from previous systems including some cotton- and some lead-covered cables - didn't know about lead ones previously.
And yes, the internet has a page on all this.