They are about 3-4 mm. I found the male upside down under what I thought was a very fine sheet web(!!) between stones at ground level. The female I found under a stone close by and I must have destroyed her web in turning the stone. They could be immature although I had assumed not - in fact they look immature on close inspection of photos.
Cyrtophora is a really big spider. I know it well with it's domed sheets in things like prickly pear in southern Spain.