From what I've read in this case it does seem OTT, a caution a quiet word in her ear would have been more appropriate for a first time, then a fine for further 'offences'. In Chelmsford there are lots of signs saying 'Do Not Feed the Birds' it then specifically mentions pigeons and why they shouldn't be fed.
Am worried in the way we are creating a more and more rules / laws / offences and enforcing no discretion manner. Cue 1984 ???
As for pigeons they are little more than flying rats, they nest in the place they were born and only move location when there is a lack of food, so controlling pigeons can be done through no public feeding and culls.
As for the health effects as a starter you can catch these from pigoens and thier feaces:
Hepatitus A, B & C
Salmonella
Weils disease (leptospirosis)
Psitticosis
Dried feaces also affect the lungs in a similar manner to dealing with coal dust or asbestos - Pneumoconiosis (Think the spellings right).
Of the above none are very pleasant, having had psitticosis and nearly being crippled by it I can vouch first hand just how unpleasant.
Funny, when started going onto demo sites about five years ago, site workers got very ansty about rats being about but didn't have a problem with pigeons as they were seen as 'cute' despite being more of a health hazard.

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