I know the answer, but keen to know what folk think.

These are the rears of our Mk2 Octavia.

from the first pic id say 50% worn

I bit difficult to exactly measure........but usually they allow 3mm thickness of friction material as minimum (i think??)........BUT i only like to go down to the same thickness as the backing plate....or until the central groove on the friction material is no longer visiable........

The pads are about 1/2 worn, so depending on your driving style a few thousand to 50K miles left in them, the discs will need doing when the pads are done mind (going by the 2nd photo)

Thanks all.

I'll bow to your knowledge, as to me they looked like they are on the backing plate of the pads?

You of course are just looking at the outer pad of the wheel. To be sure (and safe) that they are OK, I'd take a wheel off and check the inner pad (also check the inner surface of the disc).

I don't think the amount of pad left affects braking performance, unlike tyre tread so you will be OK unless the backing plate touches the disc. Obviously change them before they get to that stage. Being the rear brakes they will wear down much slower than the fronts.

My rear seem to be wearing faster than the fronts. Loads of pad left up front but the rears look like they need done soon. Something sticking?

Car went to an independent local garage recommended to us. Again SWMBO took the car in

Rears were 85% worn, and the old rear pads shown to her being removed and given to her to take away. New ones on for £55 fitted.

They even check the fronts done by Kwik Fit, and advise everything else is fine.