Is this person competent?
If we look at what is happening we can uncover motivations and move on to preventing this sort of thing happening again.
The person is either doing DIY or they are there purely to repair the chimney. If DIY then no Health and Safety at Work Act to worry about you might think. Well I don’t ‘worry’ about the Act, it’s there to protect me from people willing to risk my life for financial gain. For DIY I should adopt the same principles as I have a duty to my Wife and my children. They need me to be alive, earning money and setting the right example. DIY is a dangerous sport and hospitals actually prepare for the influx of hapless, well meaning DIYers on bank holidays. We should focus more on the people that rely on us than rushing the little task that could get us paralysed. Gravity works in the same way whether we are at work or at home.
If the guy is getting paid for the job then he is taking work from companies that would do the work safely. He will have prices so low that the client thinks that the right way is way too expensive. He will have used terms like ‘safety has all gone too far’ ‘ it isn’t worth it for such a small job’ and ‘ ill be done in a quarter of the time’. The reputable companies don’t stand a chance. This person will then break the law, put themselves at significant risk and the house holders at risk of finding a broken person laying on the ground when they return. If he doesn’t fall they both go away happy in the knowledge that they have got one over on the system, saved some money/ made more profit and nobody is any the wiser.
I’ve no idea how to stop this particularly in a recession but don’t employ people like that. If they will cut corners with their life, if they care so little for their families, they will do a half assed job.