Most of the annoyances in this thread were caused by inadvertent thoughtlessness or stupidity. That doesn't stop them being irritating, but they are understandable and, in most cases, forgivable.
I regret that I am reporting an example which was entirely deliberate and which I find very hard to forgive. It happened at Colchester on Saturday 21st April, 25 minutes before the zoo closed. It was a beautiful day and the zoo had been very busy. A lot of visitors were taking photos and I saw several people with much fancier camera gear than mine. As I explained shortly afterwards, I was particularly interested in the red-backed sakis, which had been fairly subdued earlier in the day, they became much more active as the zoo became quieter with a lot of jumping, playfighting and several matings. People who know Colchester will remember that their enclosure is viewed through windows on both sides, from the path separating the sakis from the squirrel monkeys, where I was standing, and the wider path past the sea lion pool.
As I was trying to photograph a particularly vigorous playfight I became aware of someone waving from the opposite window.
I saw that it was a man, holding a small child and waving vigorously. He had a big grin on his face, as did his female partner. It wasn't a single wave and a smile, it was a prolonged and deliberate attempt to appear in my photos.
I still don't understand why he was so pleased with himself and so intent on attracting my attention. I am glad that I did not react to that provocation, but I internally christened him Mr Richard Head, and then abbreviated that name
I was tempted to show one of pictures showing his face and expression: but I realised that this would be unwise and after consulting Sim, I have chosen these two images because most of their features are obscured and I have also concealed what remained visible to avoid controversy. Fortunately such crass behaviour is very rare. We have to remember that most zoo visitors are decent, sensible people - just like we are.