What type of plant this is and is it poisonous (and, if so, in what quantities)? The pictures were taken at Gullane Bay, Scotland. The plant is widely present in that region.
This is common sea buckthorn, Hippophae rhamnoides. The blueish leaves and the orange berries are unmistakable.
It occurs mainly in coastal regions, but is also cultivated throughout the world. The berries are processed to all kinds of food. In their natural habitat in Northwestern Europe, the berries serve as a food source for migrating birds that fly from Scandinavia to the UK or the Netherlands. However, because the berries are often rotting and contain alcohol in september, sometimes drunk birds can be observed.