very unlikely your pigeon will cr*p on her washing but it is better to let out twice a day than leave them out all day. If they are out all day they are more likely to suffer hawk attacks etc
I remember a friend telling me his neighbour had complained about her washing being cr*p'd on knowing it wasn't his birds so he told her to come round and point out exactly which one done it and it wouldn't do it again, of course she couldn't identify any culprits!
I think there has been an article written on here somewhere but its of no interest to me so i've never bothered to read up on it.
Where are you then tiler?
the picture would make a great loft but the main thing you would need in it is ventilation, false ceiling and partitions/sections for the birds as well as the normal nest boxes and perches.
I hope unikon will be re-embursing the members that have been elliminated from races, out of the season averages etc etc due to the failures of there equiptment and incompetence in sorting the problem!