Last year, the US Department of Defense banned its personnel from using portable USB drives (thumb drives, memory sticks, insert jargon of choice), a decision it is on the verge of partially rescinding.  After a spate of incidents in which data was mislaid as a result of employee negligence, the DoD opted for this relatively simple measure in order to increase operational security (OPSEC).  Someone should have impressed upon Houria Chahed Chentouf the importance of keeping such devices safe and secure:

The court heard she accidentally dropped a memory stick containing the documents when she was being questioned at Liverpool John Lennon airport on October 16 last year after arriving on a flight from Amsterdam.  The memory stick, which had been concealed in her clothing, contained more than 7,000 files including an explosives manual for 'The Brothers of the Mujahadeen'.  The device had been tied to an inner sleeve of her burka, but fell out as she reached down to scratch her leg, prosecutor Simon Denison told the court.  The following day she was arrested at her home in Longsight [Manchester].

Subsequent searches of her home found a handwritten note extolling the virtues of suicide bombing and forensic digital evidence of her support for online shuhada.   The 41-year old was sentenced to two years in custody but freed immediately on account of serving over a year in remand.  The Guardian report suggests that a history of mental illness may have mitigated the sentence and the court accepted that she was unlikely to have been planning any terrorist acts off the back of her 'mini-encyclopaedia of weapons-making'.

You'd have to be slightly unhinged to attempt to smuggle a small electronic device on your person through an X-ray machine in the first place (it looks like a SanDisk Cruzer Micro 4GB, he says, with his geek hat on).  Unless there were some rare jihadi gems on the drive, why bother even transporting the data in this form?  We have internet in the UK, you know, assuming you don't live in Wales.  It's also mighty careless to let slip your device just as you're being questioned by security, unless you really wanted to be caught, of course.

As a result of Chentouf's naiveté, counterterrorism police were led to other computers in the UK and Netherlands, and spent 12000 man hours translating recovered documents from Dutch and Arabic.  Whether this resulted in further arrests is not stated but Detective Chief Superintendent Tony Porter had this rather flat assessment of the investigation:

We do know she has got known and established links to extremists abroad and that puts us on notice to be concerned.  She is on our radar and she will know she is on our radar so I think we are in a better position than we were a year ago.

No, I don't know what that actually means either.  Evidently, she was not part of any major plot, or a more canny co-conspirator would have told her about Google Docs or some other form of online document storage, and insisted she left the offending hardware at home.  Luckily for the average citizen not all wannabe jihadis are super-geniuses.