a mystery

So what happened here?  This is on the bank at the side of the house opposite.  What's the danger?  I suppose, conceivably, someone might have thrown a bucket of whitewash into the hedge, but why?  And what would be so threatening about it?  (other than, I suppose, the fact that it might still have been wet - but then, not many people, probably, would have gone clambering into the bushes to find out.  Conceivably, I suppose their dogs might have done).  One more mystery chalked up against the man who lives opposite (something in finance, here and in New York, with a large assortment of cars.  The bargain second-hand Aston Martin that he purchased the other week seems to have been quickly exchanged for a Porsche).  This auto enthusiasm is probably entirely unrelated to dangerous white paint.