Early last Wednesday evening, Phil Harrow, a British blood service courier from Toxteth, Liverpool, was sitting in front of his computer in his living room, his attention occasionally distracted by the sounds of the local children playing football on the street outside his front window on Cedar Grove.

At about 5:30 p.m., the peace was shattered and the children scattered in terror. “Eight armed officers, dressed in black from head to toe and wearing body armor and ski masks, jumped from an unmarked white van, screamed at the children to get out of the street and battered their way into the house two doors down from mine,” recalled Harrow.

Within minutes three unmarked police cars and four large yellow police vans had cordoned off the street and about 30 more officers were shouting at residents to stay indoors with their doors and windows shut.

Three Asian men were arrested and quickly driven off.

It was a pattern repeated across the city and the northwest of England as police swooped simultaneously as part of Operation Pathway, which was targeting an alleged Al Qaeda-driven terror plot aimed at unspecified targets in Britain, to be carried out as early as Easter.

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The arrest of the 12 men — 11 Pakistanis and one Briton — had been rushed forward because of a career-ending blunder earlier that day by Bob Quick, the Metropolitan police assistant commissioner who was Britain’s chief anti-terror officer.

Quick had been running late for a morning meeting with Gordon Brown, at which he was to tell the prime minister about the raids which had been planned for 6 a.m. the next day. In the taxi on the way, he was reading a document headed "Secret: Briefing Note Operation Pathway." Quick was in such a rush that he forgot to put the document back in its folder before he got out of the cab.

A photographer snatched a picture of the document which was then transmitted to media outlets around the world. The operation had to be hastily brought forward by 12 hours.

Thankfully, Quick’s error had serious consequences only for himself — he resigned on Thursday morning — but it added unnecessary drama and danger to an operation that had already been a close-run thing — and which security sources fear is part of a much bigger threat.

The trail to the Manchester raids is thought to have begun last December with the arrest of 14 suspected Al Qaeda terrorists by Belgian police.

Officials believed a homicide bombing aimed at a two-day summit of European leaders, including Brown, was imminent after learning that one of the suspects had received a green light from his paymasters abroad.

During their detention, few of the men were prepared to cooperate with the Belgian authorities but one — whose identity remains a closely guarded secret — was willing to talk. In a series of interviews he described how he had been personally “tasked” to carry out a homicide attack in Belgium. His instructor was Rashid Rauf, a fugitive on the run from British police in Pakistan.

The would-be bomber said that the Belgian plot was just one of a number of large-scale attacks that Rauf had planned across Europe. The targets were unidentified cities in Belgium, France, Holland and the U.K.

Interviewed later by a member of MI5, the suspect said that all he knew was that Rauf had dispatched a mastermind — whose pseudonym he gave — to a British city to make preparations for an attack. His tip-off was vague but it sparked one of the largest manhunts in MI5’s recent history.

Rauf, who was born in Pakistan but was brought up in the Midlands, has already been linked to a series of alleged high-profile Islamist terror plots, including the failed July 21 homicide bomb plot that targeted London in 2005.

Despite this known track record, Rauf’s real importance had been underestimated. About four years ago he became Al Qaeda’s director of European operations.

Last November Rauf was reportedly killed when three American Hellfire missiles from a CIA predator drone destroyed a mud-built bungalow in a village in North Waziristan, in the lawless tribal lands that span the border between Pakistan and Afghanistan.

Aerial photographs taken by the Americans after the missile strike show a body, originally thought to be Rauf’s, covered in a shroud being carried from the rubble. But original assessments that he is dead have been revised. “There is nothing definitely to say he’s actually dead,” said a senior Western intelligence official last week.

“It may take a long time to find out. We honestly don’t know.”

Pakistani intelligence officials remain convinced that he was killed in the strike.

A few months earlier Rauf had sent several cells to Europe to carry out a series of linked attacks which were driven by Al Qaeda’s hatred for Barack Obama. Informed sources said it is now believed that the alleged northwest cell was part of this Europe-wide network.

The suspected members of the northwest cell had first came to the attention of MI5 about two months after the thwarted Brussels attack in December.

Click here to read more on this story from The Times of London.