LONDON, England – One day after Lord West’s ominous warning of one  ’great plot’ being monitored by UK security forces, there was a reminder today  of the terror threat at the other end of the scale.

 Nicky Reilly, a 22 year-old convert to Islam, admitted launching a failed  suicide bomb attack on a busy family restaurant.

 The attack was carried out not in London, or in any other of the UK’s major  cities, but in Exeter, a town of just over 100,000 people in the southwest of  England.

 Reilly had never travelled to Pakistan, for instance, to receive training; his  research was carried out on the Internet. Nor does it appear that he was part of  any cell - though more on that later.

The Old Bailey heard that Nicky Reilly entered the Giraffe restaurant in Exeter on a Thursday in late May carrying six bottle bombs, three containing caustic soda, three containing kerosene. He was also carrying nails packed around the devices to maximize the planned carnage.

CCTV footage shows plenty of people inside the restaurant as Reilly walked in, including a table of two women, one of whom is seen spoon-feeding her baby in a highchair.

Reilly made his way to the toilet cubicle to prepare his devices - which began to explode as he was doing so. He staggered out of the cubicle bearing serious facial injuries and was arrested by police.

Nicky Reilly was a convert to Islam who took the name Mohammad Abdulaziz Rashid Saeed-Alim The court heard he became a Muslim in his mid-teens and that over time he became drawn to violent action and the idea of himself becoming a martyr.

It’s well-established that converts are of particular interest to intelligence agencies. Security officials tracking the terror threat say one in ten of those they are concerned with were not born into Muslim families. In Reilly’s case, though, it’s only part of the story.

That’s because, in the words of his defence team, he has “rather simple characteristics.” When he was interviewed by police he was treated as a “vulnerable adult.” According to his mother he has a mental age of about ten and suffers from Asperger’s syndrome.

She believes he had been “brainwashed” into carrying out his attack. Police statements appear to back that up. They say he was “preyed upon, radicalized, and taken advantage of” by extremists in his home town of Plymouth.

Perhaps more worryingly he was also in frequent contact with two individuals over the Internet from whom he received encouragement and information about the attack.

One of the conversations included a discussion about the type of person to be targeted: public servants like the police, or ordinary citizens. In the end, the decision was to target the latter.

Police say they are still trying to trace Reilly’s Internet correspondents. It’s believed they do not live in Britain.

Reilly will be sentenced next month when the judge will have to weigh the significance of psychological and psychiatric reports promised by the defence. In doing so he will have to decide to what extent violent extremists are now deliberately targeting some of society’s most vulnerable individuals to carry out acts of terrorism.