The electric fence was not enough. Overnight a Badger, or perhaps an army of Badgers broke in and worked away beneath the enviromesh clawing and munching on our carrot crop. The only solution was to build a corrugated iron corral all round the plot. Sadly we still need the enviromesh in place as our corrugated iron is many times re-used and full of holes, not Badger sized but plenty big enough for a root-fly to squeeze through.