House sparrows

Can someone advice me on this subject. 
I am a builder and got asked to repair some roof tiles hanging dangerously at the end of a roof. So I advised the owners replace the sand and cement with a dry verge system. 
on the day I started the job I found a nest with 2 young in it so advice the owner to cancel till they had left. I have now returned 3 weeks later to find the nest empty.  How ever I did find a dead mature bird at the entrance, the nest is 2 tiles back. So as the nest was empty I completed the works. That night a neighbor posted a nasty letter to the owners complaining about my actions. As they done this at night and did not leave a name or a contact number I can’t reassure the nest was empty. As the owner was very upset about the neighbors actions I returned today and removed one dry virge were the nest was. Now my question is when can I compete works.