If the scaffolding contractor knew that, in his absence, a child had been able to climb out of a window, crawl onto the scaffolding and walk along it over a glass roof, I strongly suspect that he'd dismantle the whole lot and walk out of the job immediately. He would know that, if the HSE got to know of it, he would very likely lose his license and possibly be fined as well. He has to pay an enormous amount of money to insure not just the scaffolding equipment but also his employees who use it. He also has to pay for Public Liability insurance, just in case someone is daft enough to let a child climb on it. You're risking a lot Liveinnan.