The daredevils are from the London Consolidation Crew and the ethos of the group seems aligned with the website they posted the blog on; Silent UK:
"We’re just like you, we have jobs, go to school, watch tv and go to bars over the weekend. However, every now and then if the urge takes us, we sometimes choose to spend our time wading in sewers, climbing skyscrapers, accessing abandoned buildings and infiltrating infrastructure.
"There isn’t a single main reason why we explore. Some do it as a quest for knowledge, others like the idea of exploring the unknown and forgotten and others just do it for fun."