On Alan Bennett waving at the window and other alarming experiences

HAVING A burglar alarm installed is a way of coming out. It tells the world that you are a property-owning member of the middle classes, fearful of losing your possessions, and of intruders. Once it's there, with the round or shield-shaped badge proclaiming its presence on the front of your house, everybody knows. I feel ashamed of it, I admit, and I hate the noise it makes as much as Michael Bywater does, who sounded off against burglar alarms in the Review two weeks ago.

The shame is the loss of innocence. When we first came to live in this London street 30 years ago, our car stood, night and day, carelessly unlocked in the gutter outside. The morning when, settling into the passenger's seat as my husband started the engine, I felt a shape rise up behind me to the sound of a croaky old voice, "God bless you sir, God bless you ma'am ... Might I just open the door?" and an ancient tramp tumbled out of the back, seems like a memory of Eden.

Over the decades since then I've been walked in on in the house a few times. Once I was woken in the middle of the night by my two cats apparently letting themselves into the bedroom. "The cats have learnt to turn the door handle," I remarked to my sleeping husband as I got out of bed to throw the creatures out on to the landing. A tremendous crashing noise followed, but I was so tired I went back to sleep without bothering to investigate. I appreciated the heroism of the cats only the next morning when my next-door neighbour came to tell me the cash from his bedside table had been taken as he slept.

Another time I chased an intruder on the stairs down from my study in broad daylight, too furious, luckily, to think about anything except driving him out. Friends opposite interrupted a man unplugging their television set. He didn't stop, he simply averted his face, muttered, "Sorry about this" and continued to attempt to get hold of their television.

We laughed together about these incidents. Nobody likes to be seen to care too much about being burgled, of course. When I was mugged - abroad - in the Seventies, one of my children told me I proclaimed my bourgeois status by my appearance and that it was to be expected that those with too much should be attacked by those with not enough. I remember being lofty myself about neighbours who put bars like expanding lift gates over all their downstairs windows, and not too surprised when they seemed to attract criminals rather than deter them. Their family silver and jewellery was cruelly taken piece by piece, until at last they moved away to the country. Who could blame them?

You don't want to be the first in the street to have an alarm. We decided to have one suddenly when my son moved out into his own house, the lodger went, too, and we realised ours would be completely empty when we went on holiday, for the first time since I'd moved here. In came the expert salesman, swiftly followed by the engineers. They did a rapid and expert- seeming job. Only, as soon as we got back from our holiday, trouble began. The light in the front yard, meant to turn on when someone approaches, took to glaring permanently, giving the whole street day for night. The reason was said to be my shrubs, moving in the summer breeze and so setting off the light. I cut back the precious shrubs, but it was not enough. The light had to be resited. After that the sensors in the house kept springing the alarm when the house was empty, and we would return from a stroll in the park to find police swarming. More engineers came, told us the first installation was quite wrong, and put in different sensors. Things seemed to settle down.

Then, about a month ago, I was eating a peaceful solitary lunch in the back garden when I realised someone was trying to attract my attention from beyond the glass front door of my kitchen. I went short-sightedly over, and saw it was my neighbour, Alan Bennett, with his bicycle.

"Alan! Come in - "

Alan, leaning his bicycle against the wall and entering gingerly: "What was all the drama, then?"

"Drama? What drama?"

"Your alarm - the police - didn't you know?"

The police? The alarm? I'd been out for half an hour at the shops, having left a tranquil, empty house and returned to the same tranquillity. But according to Alan all hell had broken loose even as I made my way towards Marks & Spencer. He had heard the frightful din and with great nobility come over to investigate. The police had arrived at the same moment, and, finding the front door open, had a look round before stopping the alarm and going away. Alan departed likewise, but kept an eye on things from his window.

"So the front door was open?" I asked, remembering the previous intruder who had fled through it. Alan asked if I had been upstairs. No. There might be somebody in the house now.

Alan: "Why don't I stand in the hall while you search upstairs?"

And this is what we did. I suddenly felt frightened and reluctant to open the doors of empty bedrooms, or go into my own study, and heaven knows what either of us would have done if I'd found someone lurking. There is something called a panic button, but the thought of using it frightens me even more than a possible person. In any case, there was no one.

Alan's kindness in coming over - twice - to make sure things were all right was characteristic. It also left me feeling bad. The idea that my burglar alarm was acting as an electronic Person from Porlock, interrupting him in the middle of a sentence or a flow of ideas, depriving the world of another Talking Head, was upsetting enough. There was another worry, too. Alan once told me he likes his friends better when they are unhappy. After a book-signing session at which six people bought my book while about 3,000 queued for his, he was so nice to me that it was almost worth it. Conversely, I've noticed he can be quite cool when I have a modest success. Sometimes I see him as a sort of social barometer. Does a smile from Alan suggest he has just read a particularly savage review of my latest work? Should I be hoping he will walk past with only a curt nod, indicating that he's heard something to my advantage?

And what does he make of our burglar alarm? Perhaps he sees it as a sign that we are getting ludicrously above ourselves, stuffing our house with works of art and trinkets, imagining that a team of thieves is about to attempt to remove the Steinway from the second floor in the middle of the morning. That we have ceased to be the simple, open people we were and are turning our backs on the colourful street life of Camden. That we are rejecting the community and barricading ourselves off into a mean little nest of privilege.

I don't know and I daren't ask him. The only thing is, I've just walked round the block and noticed, with what relief I need not explain, that a burglar alarm has appeared on his house, too.

Neal Ascherson is on holiday.