Asking for a friend. Both gardens are small. The neighbour had a gentle slope uphill from his house to the back fence. But he has levelled approx 16ft of ground near the house for an extension and piled this removed soil at the end of his garden, held in place by a new brick retaining wall (with steps up to it). The result is that where previously, you wouldn't see each other over the 6ft fence, now the neighbours look chest & head over the fence! My friend is hating the loss of privacy and being overlooked. There is no soil touching the fence as the new retaining wall runs alongside it. The neighbour's extension has full planning permission. There's nothing that can be done now as the building work is almost finished. I know there're rules around decking height, but it appears it doesn't matter if you move soil around. Anyone else had experience of something like this?