This is an example of the silken spinning that the spider uses as a refuge and sits in to wait for prey:
It lays its egg sacs wrapped in yellow silk on hard surfaces in the autumn, and the spiderlings will hatch out in the spring. If you look closely there is a spider in there too!
|Zygiella x-notata egg sacs|
The spider recording scheme shows few records for Glamorgan, but I have seen these in a number of locations including Cardiff, Barry and Rhoose, so I am pretty confident they are in fact quite widely distributed.
Source: Spider Recording Scheme/British Arachnological Society (2012) Website and on-line database facility