I did a circular walk up onto Table Mountain above Crickhowell in the Black Mountains. On the way down I nearly stepped on this caterpillar. I've searched through the butterfly book I have which has caterpiller drawings, but it doesn't really properly match any of them. Another thought was if it was a moth. Size was approaching 2 inches/5 cm from memory.
I think you may be right. I've checked sets of images for all of the possibles given on your link. Nothing was obvious using the group names. I then tried the full name and found an image which linked to this page - http://www.gutefrage.net/frage/welche-raupe-ist-das-den - (in German - but Google can translate??!!). It is the best match I can find. Taken from a slightly different angle than my images but the three white spots near the ?head? end seem to match the set of six in my view.
I know moth ID is a headache, but hadn't realised their caterpillars are as bad (or worse, 'cos of the instar thing).