National Trust volunteering - a dangerous sport??

Today we were coppice couping- protecting young tree stumps from deer by dead hedging around them.  While cutting down hazel to make the hedges one of our team came across this mortar bomb - apparently not detonated!  Luckily most of us were working in other areas so we kept well away from it.  I think it has now been reported to the authorities so it may well make the local news.