Steve Hayes wrote:

I would be interested in knowing how widespread is the idea that
"landline" excludes "cable"

When talking about voice service, I wouldn't distinguish, especially as
Virgin Media (tend to?) use a "shotgun" cable so the voice circuit is
delivered over twisted pair from the street cabinet.

But when talking about Internet access I'd distinguish broadband over
coaxial cable (DOCSIS) and broadband over twisted pair cable (ADSL/VDSL).

All from a UK perspective.