Has a crime actually been committed? It seems on the face of it that the property may have belonged to the people who set fire to it and also demolished it. Are you allowed to burn your own house down? Probably there was no insurance, anyway. And the house wasn't listed, only listing. Yes, it all stinks to high Heaven but I'll be surprised if any serious prosecutions are brought. Do you need planning permission to demolish a house? Probably, yes, so there might be a retrospective case for the council but that might be about it. I suspect this outfit knows very well what it is doing. That's why they live in a gated establishment. Be nice if they were in a different gated establishment, perhaps, with no matches.