Cryptic Bark Argiope

Size about 11mm. Black spider with a white marginal abdominal band. It builds a typical spider web with very fine silk. It was found near a North facing cliff near a derelict quarry. Update 9/4/2017: Yesterday, I found several individuals. Their sizes can range considerably as I have noticed. One was almost 15mm, while other ones nearby just about 4mm, with corresponding size of their web. The large one seemed to be attracting insects by vibrating its web while being in the middle but hardly visible because it seemed blurred out. The web is quite regular, and looks like the spider used double stitches, probably some form of stabilimentum. Other predatory spiders and large mosquitos around. Update 4/7/2017: Indeed a very common spider. It seems to be a social spider, too, often found on busy tree trunks with lots of insect traffic. One spider rarely comes on its own. Colour varies. Web shaking is very deliberate and can be stopped from one moment to the other.