Hmm, that’s deffo not on. I suppose it all depends on the appetite you and your neighbours have for a dispute.
I would say if that land doesn’t belong to him alone and he hasn’t sought permission then it is a nuisance and you/your neighbours would be at liberty to intimate a claim against him and/or seek an injunction for the removal of the waste.
However, I think you’re probably looking at £20k+ to secure an injunction, so you’d all have to decide whether or not the inconvenience was worth it.
If it were me, I’d be having a polite word to ascertain how long he intended it use the land for ‘temporary’ storage, and hint that if it goes over that you’ll be clubbing together to hire a licensed waste removal company and then recovering the cost from him.
It looks like it’s a private road on an estate – is there anything in the title register for the properties which requires residents to keep the area in good repair? If you’re occupying under long leases and there is, you might be able to get the freeholder to exert some pressure.