I did a bit as banksman for a tower crane running on rails at the New Bridewell in Bristol centre .. a great 6 wks hol job in 60's ... slapping the chains on reinforcing steel off an artic, crane trollied to extent .. klaxtons blaring .. wheels lifting off tracks (H&S wots that then ?) .. Brian the crane driver doing his tribal dance with the remote control on the scaffolding .. couldn't drop the rotated load .. over a main road ....