In article , "Lobster"
says...
Mike Dodd wrote:
Is it common for stud partition walls in relatively new-build houses to have
only vertical beams (apart from top/bottom, of course) thus allowing a
vertical drop of a cable?

No, uncommon I'd say.

You ought to be able to tell where the horizontal members (noggins) are
by tapping the wall; if not you can get electronic stud-detectors at B&Q
etc (can't vouch for their usefulness though!).

Even assuming there are noggins, it's not that difficult or invasive to
get round them; essentially you need to end up with a small hole in the
plasterboard above and below the noggin so you can get a drill through
the noggin.

Why not just cut out a strip of plasterboard across the noggin,
saw/chisel a groove in the front, run the cable then patch the
plasterboard?

Afterwards the holes can be repaired pretty much invisibly,
(providing you don't need to wallpaper the whole room again!)

Cut a couple of flaps in the wallpaper with a sharp knife, carefully
peel the paper back, replace when you've finished butchering the
wall?