On 09/11/2020 20:34, F wrote:
I'm about to add a security camera to the back of the house which will
mean a fourth Ethernet cable running parallel to three others. Is there
any kind of trunking/conduit/whatever that I can fix to the (brick) wall
to take the cables and tidy things up? It would need to be around 15m
long and accept internal and external corners.

Er, conduit? Screwfix, Toolstation, etc. For that sort of length, it
will be neater to use the "proper" stuff.