Pied Wagtail Roosts

I recently came across a situation where pied wagtails were roosting on an industrial site in England and were getting trapped in an area that had been enclosed by anti-pigeon netting.  A number of dead wagtails were found.  This was not the intention of the company concerned and they are now taking steps to address the problem.  However I was wondering - given the pied wagtail's prediliction for communal roosting on buildings - whether this problem has been encountered elsewhere and if so how frequently.

I was also wondering what the legal position is.  My understanding is that in England and Wales it is an offence to kill a wild bird intentionally so - as there was no intention here - an offence has presumably not occurred, however unfortunate the situation.  In Scotland I believe it is an offence to kill a wild bird either intentionally or recklessly and I suppose it could be argued that it would be reckless to maintain the netting in the scenario described above,knowing that it is likely to trap and kill pied wagails.  Is this a correct summary of the relevant law or is there something else I am missing?