Re the issue of concentrated shot fall on estates where there is commercial driven shooting:

If there is concern about partridges ingesting lead shot, there's a fairly simple method to determine whether it's a serious issue: Examine the gizzards of all partridges shot on the estate. This was done on a quail research facility in the US where a large number of birds were shot in a relatively small area. 241 gizzards examined . . . 3 contained lead pellets.