Kevin,

"September 11 just needed a few airline tickets, and some boxcutters, and in this instance a few people with a minimal amount of flight training, which had been supplied by commercial organisations."

It was 18 months to two years in the planning Kevin.

"Finance? Traditionally that's been largely stuff like bank robberies and protection money. The analogy is more with the Mafia than with a regular army. Self financing."

Go this route Kevin and you will set off at least four trip-wires that I can think of, think of the interfaces required to make this work and keep it secret. One of the reasons those involved with September 11th pulled it off was because the finance they were using was "clean". Back tracks subsequent to 11th September have made this even more difficult to achieve.

"Training is done as and when it is needed, and can effectively be invisible when you are dealing with maybe half a dozen people at a time. "Safe Havens" might be helpful, but they aren't really needed."

Really Kevin! Amazing! love to know how someone can be effectively invisible while learning the bomb makers trade. Guess people never needed those training camps in Libya, Lebanon and Afghanistan - perhaps they were more social clubs than anything else.

"The essential thing is a reservoir of sympathisers in the wider community."

Oddly enough Kevin for the operations you predict that Al-Qaeda will embark upon, using your "invisible seperate cell" philosophy, the reservoir of sympathisers in the wider community hinder rather than help as they constitute the most serious security risk (Best example of this that I know of was Northern Ireland - I am not talking about informers, purely observation and inadvertant slips by the reservoir of sympathisers in the wider community).

From what you say above you seriously under-rate the work done by various counter-terrorist organisations - You shouldn't, certainly the potential terrorists don't.