Thanks all.
Internal routing
Even with Powerlines or wireless you still need to run a length of cable from the master socket to the router. If you have nice set up this might just be a few inches but you still need a power socket near enough to the master plug. I’ll look into whether I could buy an extension cable for the thin router power cable.
External routing
The house had this before but the cable had deteriorated over time. Because the house is old and has had several stages of extension, the ideal location would still require drilling right through two thick external walls to position it – a bit more of a job than I’d like.
I’ll see what I can do with the indoor wireless options but I’m still limited by those external walls for impairing the signal. Oh, and it needs to be small child proof – why do they like tugging at cables so much???