REVEALING top secret MI5 files about the July 7 bombers to the families of those killed in the attacks would be “impossible”, a hearing was told.

The hearing deciding the format of the inquest for the victims was told that investigating whether the security service could have prevented the atrocities would involve “handing over the keys” to MI5’s Thames House headquarters in London.

Neil Garnham QC, counsel for the Home Secretary and MI5, argued that examining MI5’s involvement was outside the scope of the inquests.

He said there would be no problem with providing highly sensitive intelligence material to the coroner and counsel to the inquests.

But any jurors could only see the material if they all underwent intrusive “developed vetting” and neither the bereaved families nor their lawyers would be allowed to see it, he said.

“It would be the security service’s position that disclosure of sensitive information to a jury is simply not possible,” he said.

“For the same reasons as for juries, disclosure to the families would be impossible.”

The bombings were carried out by four suicide bombers from West Yorkshire, including Mohammed Sidique Khan, of Dewsbury, and former Rawthorpe High student Jermaine Lindsay.

The coroner, Lady Justice Hallett, asked whether it would be possible to restrict the intelligence material discussed in the inquests to that related to the July 7 attacks.

She said: “The families want to know why the decisions were taken in the way they were, and to put questions.”

And she also revealed that she went on the internet to read conspiracy theories about the July 7 2005 attacks on London. Proceeding.