This is a natural nest, built by the swallows that return to Yew View every summer, from Africa.  They usually repair and add a little to it each year, before lining it with feathers, grass and straw. In a good year, they can raise three broods. The workshop can be dark at times, so you may see the camera switch to IR, which actually illuminates the area nicely, giving good views of the adults and their brood.