There is a thuggery fish on the loose (how big !?)myself as an Iraqi British ,it is my duty and responsibility to inform you that this individual highly dangerouse one ....and it is much easier for us to sus out the thresh hold of the danger and whether it is worthwhile to follow it or not !
I threatened him verbaly and almost p...he did back off !
My fear his work it involves taking Americans and British tourists around ....I did n't like the slight mercky wink in his eyes when he revealed this (here he means he could do harm,if he wants to !)
By the way he is a typical bearded one and extrem in his view very anti US !
It will be interesting to know what he has on his PC !FIRST ( I suspect he is one of the sleeping cell)
Iam willing to give you hand , if you realy wants to !
I was going to inform the Brit , US ,or Italians , but not sure how serious are they and might discarded as I am a nut !
This is for the first I reveal it to anyone .

A.B., the Security Service (MI-5) should be your next phone call or e-mail (I guess they have a website?) if this guy is in the U.K. If you think he's more of an immediate threat you should probably go to the police instead, but MI-5 is the better choice if this guy isn't ready to walk into a Tube station with an explosive vest. Either way, be prepared to give them as much specific information as you can--name of the guy, where he works, his contact information, what he's said that's threatening. If you can provide something beyond innuendo or "gut feeling", MI-5 will probably be more inclined to listen to your story and open a case. Be prepared for hard questions; as you alluded to, they get "nut jobs" and "poison pen" allegations all the time, and they have be able to sort out the real nuggets. They should also be able to safeguard your identity, if you're concerned about that. Oh, and don't expect to hear anything further from MI-5 once you give them the information. It's likely that they'll do what they need to do without you ever being aware of it.