The find was the first indication of any plan to attack the English Defence League rally in Dewsbury even though one of the plotters had been under "low-level" surveillance by police and security services five days earlier.
Jewel Uddin, who was being watched because he had been spotted collecting cash on the street for another terrorist plot, had been seen by undercover police officers walking into a shop where he is believed to have bought a set of knives that were to be used in the attack.
Uddin, 27, was among six people who pleaded guilty via video link from prison at Woolwich Crown Court. Bomb-maker Omar Khan, 28; Zohaib Kamran Ahmed, 22; and Mohammed Saud, 22 - who are all unemployed - and gym workers Anzal Hussain, 31, and Mohammed Hasseen, 23, admitted preparing for the terrorist attack on the rally in Dewsbury, West Yorkshire, on June 30 last year. The judge, Nicholas Hilliard, QC, said the six could expect significant prison terms when they are sentenced in June.
Hussain's brother was jailed last week after he travelled to Pakistan for training for a separate suicide bomb plot. He was part of another group of Birmingham-based jihadists caught before they sent eight rucksack bombers into crowds for an attack designed to rival the July 7, 2005, attacks on the London transport network.
Poor planning - and an early finish for the Defence League rally - averted the Dewsbury attack using a nail-filled homemade firework bomb that experts fear could have led to a race war between Islamist radicals and the fragmented extreme right-wing movement.
The bomb was filled with more than 400 nails and ball-bearings and police believe the men could have intended to light the fuse and toss it into the crowd. It had the potential to maim or kill.
It emerged that the potential bombers had used the internet to plot their attack and had done searches on the leader of the party, Tommy Robinson. Robinson did not attend the rally and his number two and cousin Kevin Carroll addressed the crowds.
However, the crowds of up to 700 people, a counter-protest by the United Against Fascism group and hundreds of police officers had all left by the time the bombers arrived in two cars.
The plotters were denied a second opportunity to attack after one of their cars was followed and pulled over by a South Yorkshire traffic policeman during a routine check on the M1 as they were driving home after a chip supper in the town.
One of the plotters had paid for cover but filled in the form incorrectly so it showed up as having no insurance. Khan was driving the ageing Renault Laguna that was stopped on the M1 with Uddin as his passenger. Police dropped them off at a nearby railway station to let them get home before they realised what they had netted.
The stash of weapons - including sawn-off shotguns, machetes, knives, samurai swords and elements for pipe bombs - as well as extremist CDs and 10 declarations of intent to attack the right-wing demonstrators were found only on the Monday.
The note - addressed to "enemies of Islam, the Queen and David Cameron" - detailed why the "English Drunkards League" was a target. "This is a message to the enemies of Allah and his messenger. This is a message to the kafir (non-believer) female devil and self-proclaimed Queen Elizabeth and her accursed jubilee, fooling a nation of blind sheep to your self-proclaimed royalty and majesty," it said.
"We have heard and seen you openly insulting the final Messenger of Allah ... We love death more than you love life. The penalty for blasphemy of Allan and his Messenger Muhammed is death."
A frantic police operation followed after the West Midlands counter-terrorism team was contacted at 6pm local time that day to try to trace the two men.
They identified Uddin through CCTV and other cameras revealed that a second car had been travelling with them to Dewsbury for the day of the attack. All six men were arrested by Wednesday evening - the five who travelled to Dewsbury and a sixth man who did not go to the town because he was attending a funeral.
The plotters were said to have been inspired by the US-born preacher Anwar al-Awlaki, who was killed in a US drone attack in Yemen in 2010. West Midlands Assistant Chief Constable Marcus Beale said there had been no failings by police or MI5.
"Based on the information we had, we wouldn't have done anything differently." Independent
