The Home Office is once again under attack for the standard of the evidence it uses to support its policies, this time over plans to harvest much more communications data.
When the government published a summary of responses to its consultation on the Interception Modernisation Programme (IMP) a week ago, it included a series of tales of gangsters busted, children rescued from abuse and lives saved by communications data.
One of the five examples has attracted the wrath of the SNP, which has accused the government of twisting facts in an attempt to justify its plans to compel communications providers to intercept, store and process all details of who contacts whom, when, where and how.
For mobile phones, that includes cell site data, which can sometimes be used to calculate the rough position of a user.
Here's the case study in full:
A walker who had become disorientated and lost in very poor visibility on the Isle Of Lewis, telephoned the Stornoway coastguards using his mobile phone. The caller reported that he was unsure of his position on the Moor but had managed to find shelter for himself and his dog. A rescue helicopter and four coastguard rescue teams were sent to the scene.
The use of telephone communications data was essential to finding this man, without which, coastguards would not have been able to approximate his location, and save his life.
The walker was 23-year-old local Malcolm Murray, who set out for a stroll with his dog Buttons on a Friday afternoon this February.
The hapless pair bacame lost in a thick fog that fell on the Isle of Lewis' frozen Barvas Moor. He at first rang his father, a retired emergency planner, who attempted in vain to find him by driving along the nearby Pentland Road sounding his horn.
The Murrays then contacted rescuers, who set off across the Moor in four teams of five men. Meanwhile a helicopter crew peered through the darkness and mist using an infra-red camera, but Murray and Buttons' heat signature was hidden by rocks and undergrowth.
A spokesman for the Marine and Coastguard Agency (MCGA) confirmed today that cell site data was also of limited use because Murray was only in range of one mast, making triangulation of his position impossible.
"It was a vast area," the spokesman said.
Murray kept in contact with rescuers by ringing their base. He listened for the sound of the helicoptor before signalling his position with the phone flash, which was picked up by the infra-red camera.
While knowing which cell he was in was useful, "the rescue was audio and it was visual," the MCGA spokesman said. "The mobile phone was most useful for keeping in contact."
He said he was unable to explain why it had been described as "essential" by the Home Office.
The SNP has noted the contemporary account of events on Bavan Moor rather calls into question the Home Office's claim Murray would have died without communications data.
"This is the Home Office looking for 'intelligence' to justify its plans just as the government did in Iraq," said local MP Angus MacNeil.
Asked to comment on the accusation it had exaggerated the role of cell site data in the resuce, the Home Office said: "The Maritime and Coastguard Agency has confirmed that communications data was used to aid the search and rescue of the lost walker."
Home Office watchers won't be surprised by this latest controversy, minor as it is. The Home Office's reputation for evidence-based policy making is poor, as amply, er, evidenced, by the recent David Nutt affair.
That controversy followed soon after the Jill Dando Institute complained its data had been prematurely used to support the government's plans for continued DNA retention in the wake of defeat at the European Court of Human Rights.
Arguments over the spin applied to the Malcolm Murray case study ignore what is most misleading: its very inclusion in IMP publicity. Mobile phone companies already capture cell site data and share it with emergency services as required. Indeed, that's exactly what happened for Murray, although by circumstance it played only a minor role in his rescue.
But with IMP, officials seek a massive expansion of data capture from the internet for long-term storage and data mining, which would be no use to rescuers on the Isle of Lewis. ®