7/7 gang ready for gunfight in 'merciless' plot of mass murder

The atrocities were possibly delayed after the pregnant wife of the terror plot's ringleader, Mohammed Sidique Khan, was admitted to hospital in Yorkshire. She miscarried on the day of the attacks, which killed 52 innocent people.

Details of the apparent change of plan emerged yesterday at the resumption of inquests into the victims of the bombing campaign, which brought terror to London's public transport network on July 7, 2005.

Coroner Lady Justice Hallett also heard how the emergency response to the explosions was marred by a series of failings that might have delayed urgent medical care to those injured.

Staff at the London Underground co-ordination centre continued to tell colleagues the incidents were not terrorist attacks until 44 minutes after the first explosion, and a senior Tube line manager could not make outgoing calls because the telephone system was overloaded.

The hearing at the Royal Courts of Justice in London was told that the bombers, Khan, 30, Shehzad Tanweer, 22, Hassib Hussain, 18, all from Leeds, and Jermaine Lindsay, 19, who grew up in Huddersfield, carried out the attacks after travelling to the capital on a train that morning.

They used bombs, concealed in rucksacks, which contained several kilograms of homemade high explosives created from a mixture of hydrogen peroxide and pepper and were detonated by a nine-volt battery.

After the attacks, police discovered a semi-automatic pistol when they searched two cars left by the bombers at Luton railway station.

Officers also found eight small improvised explosive devices, four of which were made from shallow dishes and the other half from tubes.

Counsel to the inquests Hugo Keith QC said: "It may be that the intention of the bombers had been to throw them if they were apprehended and came under attack."

The devices were made in a ground-floor flat in Alexandra Grove in Leeds, rented by Lindsay, which the terrorists had converted into a bomb factory.

When police raided the flat five days after the attacks, they found chemicals, extracts from a notorious bomb-making guide called The Anarchist's Cookbook, and an improvised detonator made from a lightbulb, wire, aluminium foil and a high explosive known as HMTD.

At least 34 milk pans had been destroyed, apparently after the bombers used them to boil the concentrated hydrogen peroxide.

The court heard that the four bombers had visited London on June 28 on a "reconnaissance" mission, but not everything went to plan a week later.

At 4.35am on July 6, a day after Khan had visited Dewsbury Hospital with his wife, Hasina Patel, because of complications during her pregnancy, he sent Tanweer a text message which read: "Having major problem. Cannot make time. Will ring you when I get it sorted. Wait at home."

Mr Keith said: "It may have been that the attack was originally planned for a different day."

The hearing began with a minute's silence for the victims, who Mr Keith said were murdered in acts of "merciless savagery".

He added: "The slaughter caused by the bombs caused not only death, devastation and mutilation but unleashed an unimaginable tidal wave of shock, misery and horror for their families and loved ones.

"Just as the lives of 52 victims were callously and brutally ended, the lives of many others have been and continue to be tormented."

The inquests, which are expected to last five months, will examine whether West Yorkshire Police, the Metropolitan Police and security services could have prevented the attacks.

The coroner will assess whether West Yorkshire officers failed to properly investigate the fact that Khan attended a terror training camp in 2001.

She will also consider whether the force properly investigated contact between Khan, Tanweer and Omar Khayim, who was jailed for life in 2007 for plotting to build a lethal bomb from fertiliser.