It looks like a Galium species or other member of the Rubiaceae. Can you get a bit out and photograph it against a plain background? It's hard to see the details clearly. Its not the temperature which rules out spurge, it's the appearance.

Thanks floral! Even from across the pond you got it! With your help I found this,

"Galium desereticum is a plant species in the Rubiaceae.[1] It is native to the states of Nevada and Utah in the southwestern United States.

........or more commonly know as Desert Bedstraw, is a subshrub forb/herb of the genus Galium"

This is smaller and faster spreading than the Sweet Woodruff (Galium) that I've planted on purpose, so I didn't know what to make of it.