If only a quiet word would do it! You soon discover that generosity is just taken for stupidity. Speak softly and carry a big stick (or in my case keep three big hairy dogs!) is my advice.Live and let live . I can't see anything that would be a 'blot on the horizon' in the photos .
If they need planning permission then perhaps a gentle word in their ear to advise might help rather than let them carry on regardless . .....a helpful neighbour is always better than an awkward one and you can choose which you want to be .