In a small pocket of Islington, north London, among leafy streets and rows of elegant Georgian houses, the calm of the chattering classes has been shattered. Concerned for their security, those willing to talk to me wish to remain anonymous. As Mr A explained: 'I don't want a bomb through my letter box.'

Their fears stem from something less obviously explosive but equally sinister. On 19 January, shiny brass letter boxes snapped shut on leaflets from Islington police station announcing the date of a high-security event that was due to take place in their area, for which parking restrictions would be necessary.

Mrs B, who has lived in the area for several years, was alarmed. 'It was a very nebulous leaflet. It didn't advise us why or what we should do with our cars, or exactly when we should move them, or whether they would be towed off.'

She phoned Islington police station to find out exactly what this 'event' was, only to be filled with foreboding. Just down the road from her house, at the Canonbury Academy, the Institute of Risk Management planned to hold a conference on anti-terrorism.

At this point, you should understand that this is no ordinary community. It has not been since December 1991 when - to the amazement of those who were on neighbourly terms with her - it was announced that Mrs Rimington, Stella, the quiet civil servant who had lived in the area for more than 15 years, was to be the head of MI5.

Mrs Rimington would not be attending the event, but Mrs B and her fellow residents showed utter disbelief at the unhappy coincidence: a conference on anti- terrorism being held only a stone's throw from the chief spook's house.

Mr A, whose house backs on to the Canonbury Academy, has long been aware of conferences and large noisy parties that in summer spill outside - 'It's made our garden unusable' - but that all seemed like a picnic compared with what was going to happen next.

As the day of the conference approached, the residents became increasingly edgy. They learnt that there might be police marksmen guarding their rooftops. Surely not, this is Islington]

At 5pm last Tuesday, the police started putting orange cones along the streets. By 7pm they had begun to rummage through dustbins and a towing truck cruised the streets on the look-out for cars belonging to hapless residents who were away or had ignored the leaflets. Mrs B was upset. 'They didn't warn us they'd be blocking the streets off.'

People were concerned about getting children to school and the effect that the sight of marksmen might have on their offspring. Mr A walked out on to his terrace and looked up to see a pair of binoculars trained on him.

'This feels more like Paraguay than London,' he said. 'If a high- security event requires such precautions, what about our permanent security risk, Mrs Rimington? I appreciate she has to live somewhere and someone has to do her job, but she should not be living in such a close-knit area and putting our children's lives at risk.'

Mrs Rimington did not go home the night before the conference. Neighbours noticed that the lights were off all evening at the pounds 350,000 house she has lived in for the past two years.

Mrs Rimington is discreet. Residents, until all this blew up, had almost forgotten she lived among them, although Mrs B does check under her car 'because Mrs Rimington took on the terrorist section and, you know, they do get it wrong sometimes'. The only time she has had any confrontation with her neighbours was about a wooden garden fence she had put up, which some people thought was ugly and out of scale.

Mrs Rimington lives a fairly ordinary life - despite the fact that some residents think she should not be allowed to - although she is not the sort of person about whom you hear people raving, 'Have you tasted Stella's wonderful meringues?' She takes her daughters for driving lessons, walks her dog and goes to local Christmas drinks parties. She has moved house within the area, but that is generally thought to be because she split up with her husband, John, and not for any reasons of security. But she has moved her letter box.

In stark contrast to her low-key approach to protection, on Wednesday, conference day, the police were on a very visible security alert. Many dressed in luminous yellow jackets, they guarded the street corners in the drizzle. Patrol cars cruised the empty streets. Mounted policemen added to the feeling of unreality. An unclaimed blue van was searched. Every passer-by was questioned. The police explained that security was tight because a bomb had once been planted at a similar event.

Residents were disappointed when the conference-goers did not arrive in chauffeur-driven limos. A number arrived by coach while the rest, dressed in suits and trenchcoats and carrying briefcases, walked there. Their identity remained a mystery. Whoever they were, Mrs B remains extremely alarmed 'that in a residential area, people are prepared to let their premises for a conference on anti-terrorism; and it's particularly unbelievable in an area where such a high-profile target as Mrs Rimington lives'.

(Photographs omitted)