Please show me where it says this on the web? I know a fair bit about Travellers -- Scottish, Irish, and a tiny bit about English, and have only heard of very exceptional cases where they were violent. Heartless scammers who will rob an old person of every dime, yes, but murders and rapists -- not that I've ever come across in my at one time very extensive research. They don't approve of violence because then their crimes become "persons" crimes and bring the law down in force, wherease mere robbery and fraud are only property crimes, and most victims -- not to mention most law enforcement officials -- recognize neither the scam nor the scammer. Most in law enforcement, at the time I did this research (a few years ago) had no idea of what a Traveller is. They could be operating in your town, and your local police folks would not know who they were or what they do.
That is probably true regarding law enforcement agencies, but the banks certainly do. When my wife worked for a bank about seventeen years ago she used to get a heads up when they came into town from the management. Check kiting, short changing and stolen checks would increase dramatically.
As for the websites that led me astray, here are a few of 'em:
http://forums.sterlingtimes.org/tool/post/sterlingtimes/vpost?id=3687
http://www.tangled.info/forum/lofiversion/index.php/t33700.html
The poster "Callisto" seems very well informed, except when (s)he gets to the part about Gypsy culture being based on being "very kind" and generous to others. I had to laugh when I read that. In my limited experience, they seem more like cutthroats than anything else, so I took Callisto with a grain of salt.
http://www.thisislancashire.co.uk/lancashire/archive/1996/04/11/NEWS5-2VQ.html
Part of my confusion stems from the word "travellers" (lower case 't') being applied to Gypsies, and I was too careless to notice that "Travellers" (upper case) refers to the other group. Anyway, thanks again for setting me straight on this! :-)