An interesting and informative debate.
I think we all agree that this debate is separated into legalities and morals. I would like to add my support and sympathy to the OP - please do not let this incident ruin your enjoyment of photography.
I hate kid's...... and would not photograph them by choice as they do not interest me at all. But I would give my life to protect them.
With 30 years on the front line of law enforcement, you learn very quickly that irate people are very difficult to deal with, there is no reasoning with them. So you can either walk away or be prepared to defend yourself as it will almost always escalate to some form of assault.
In the UK you can use as much force as is reasonable to protect yourself, another or your property. Unfortunately that means that you should almost wait until the offender has a go, then you can match that. In this case I feel that the OP went about it as best he could. It is difficult to remain calm in these situations without training in conflict situations, so I applaud him.
As mentioned before, offensive weapons are illegal. A camera is not an offensive weapon as it is not designed or manufactured to cause harm - a flick knife or a knuckleduster is. On another point, CS gas or pepper spray can be classed as a firearm in the UK!
I have been accused of being a paedophile when taking pictures in a park. So I can relate first hand to the OP. As I said, I not a kid person, so they weren't the main subject. A woman, rushed over and started having an irrational go at me. I let her rant on for a while but remained calm, this annoyed her even more and she grabbed the front of my 500f4. It was then that she got told in no uncertain terms to desist or suffer the consequenses. She then backed off and yelled that she was calling the police. I gave her the phone number and waited for the police to arrive. In the end she was warned by the police and that any continuance on her part would leave her liable to arrest. After she calmed down I was able to explain to her exactly what I was up to and she apologised. If she asked at the beginning this would never have happened, if I had walked away, she would have told everyone that she had chased off a paedophile.
I will do whatever it takes to protect myself, family and property from irate people, but will not take the blame for instigating situations just because I am enjoying my hobby/profession perfectly legally. I will absolutely not stand for being accused of being any sort of criminal.
Not judging anyone here, just giving another view and example. Just don't let bullies walk all over you. Either know your rights and stand up for them yourself, or call the police to assist.
In the UK, be aware that we have Community Support Officers and they are not trained police officers and really, despite their best intentions, don't have much of a clue about the law in this regard, so please be patient! They cannot make you delete pictures, touch your camera or stop you from taking pictures of them or anything else in a public place.