That sounds like a failure on the part of whatever authority licensed the scaffolding work. Picking one from a quick search: Greenwich, for example, says that

That sounds like a failure on the part of whatever authority licensed the scaffolding work. Picking one from a quick search: Greenwich, for example, says that "Noisy work is prohibited on Sundays and bank holidays", and explicitly mentions "Erecting and dismantling of scaffolding" in its examples of "noisy work". (https://www.royalgreenwich.gov.uk/info/200205/pollution_and_noise/654/noise_from_building_works https://www.royalgreenwich.gov.uk/info/200205/pollution_and_...) Presumably other authorities may have different rules, and they may or may not be effectively enforced. But in principle, at least, it's not a free-for-all.