Hats off to Saudi intelligence.
It seems the man who foiled al-Qaeda's latest underpants bombing plot was one of their agents. We also have the Saudis to thank for uncovering the printer bombs intercepted in Dubai and East Midlands airports in late 2010.
It seems that all these devices were the work of Ibrahim al-Asiri, the master bomb-maker who is probably the most wanted man in the world right now.
This is a terrorist so devious and ruthless that in 2009 he implanted a device in his brother's intestine. Detonated by a mobile phone signal the bomb blew the brother apart. However he failed to kill his intended target, the Saudi security minister.
Al-Asiri's devices are worryingly good. When East Midlands police first looked at the Hewlett-Packard printer bomb they dismissed it as a crude test run.
The Emiratis had found an almost identical device and concluded it was one of the most sophisticated bombs they had ever come across. They advised the British to look again.
The circuitry in the bomb was identical to the circuitry in a printer. The explosives in the ink cartridge had the consistency of gloopy ink. In other words under X-ray the bombs looked like ordinary printers. Again it was human intelligence - in this case a tip-off from the Saudis - that saved the day.
No-one in Western, or Saudi, intelligence, will rest easy until al-Asiri has been taken out.