The ethernet cable is now in the bin. Tried it on next doors laptop to router and no joy. I am running via wifi and speed has been between 32 and 36 (tested at various times over 24 hours) so the cable was the issue. I will buy a new cable tomorrow sometime.
I need to contact PN to cancel the engineer and will do that in the morning, allowing me to be absolutely certain speed-wise.
Thanks to those that offered help/advice.
The only problem I have now is who to give the 'fix' to.
A float tip is pleasing in its appearance and even more pleasing in its disappearance. Growing old is inevitable...But growing up is optional.