Dangerous(?) Building Work

I'm new to the forum and while I haven't contributed so far, I hope to do so in future.  I've found some good recommendations for tradespeople here so am keen to offer something back.

Reason I've registered today is because I have a question about some building work that is going on at the property next door to mine and I thought some of you might be able to help.

The building work in question is the conversion of a top floor flat.  There is scaffolding erected and the builders have today started stripping the roof tiles.  They don't have a skip or a chute and are instead using a plastic garden container (the type one would normally use to collect weeds, earth, etc.) on a pulley to transport the tiles, rubble etc. to the ground floor.  It doesn't seem to be working very well since quite a lot of debris has ended up in my front garden and on the pathway in front.  I'm told at one point the container split, showering the builder underneath in debris.  Since then, they've dispensed with the container/pulley system and have simply been throwing the waste into the bag below.

By the time I realised this, they had left for the day so I wasn't able to speak with them.  I've spoken with my neighbour (who owns the ground floor flat below where the work is taking place) and she is trying to find out the number of the property owner so we can talk to them.

I called the council to see if I could find out if there were any regulations around using a chute and a skip but they couldn't help and referred me to the HSE.  I couldn't find any information on their website re. this and they don't take calls.

If you've got this far (thank you!), I guess my question is: does anyone know if there are any regulations in place that dictate one must use a chute and a skip? I'm annoyed about the debris and the dirt on my property but I'm mostly concerned about the fact someone could be hurt if they were hit by anything falling.  I'm not looking to raise a complaint and will happily talk to the owner of the property about my concerns but it would be helpful to have something a little more concrete than "this seems pretty dangerous" when doing so.

Any thoughts gratefully received!