I found a pair of these Long Tailed Tits, busily buzzing around collecting mouthfuls of moss and spiders webs. They were quite content to come quite close as they rushed around building their nest. They weave all this together and when their 8-12 chicks hatch and grow, the nest will stretch to allow them to all fit.
After building the nest, they line it with masses of feathers to keep the babies warm.