I've recently moved to the area and had an odd moment earlier that I though I'd share.
A guy knocked on my door asking whether I needed any gravel, obviously it didn't exactly feel legitimate and I declined. After, it got me thinking whether they were 'casing' the house to see if anyone was in but after a Google search it seems like this sort of thing has been reported in Breckland a few times where the guys offer a good price for gravel but then raise the cost later.
i wondered if anyone else had been approached today/experienced this sort of thing before in the area?