IT'S DAMN difficult, lying to the police when they've arrested you. I've tried and I know. It wasn't so much the impropriety of it all - it was the fact that I couldn't remember who I was meant to be or what it was I'd done. Faint impressions of information kept drifting through my mind: I lived in north London; I had a five-bedroomed house; I was to deny the charge - that was it, I was to deny the charge . . .

Why was I even trying to lie? Because I'd volunteered, that's why. In fact, I was helping the police run their week-long course on New Techniques in Interviewing, in which they train their officers to use new, sensitive, psychological methods on suspects in the interview room, rather than the old tried and tested routines of shouting, threatening and cajoling, as immortalised in countless television cop shows.

I was a stooge, pretending to have committed a crime, the details of which had been worked out the day before by two course members and to which I would not confess unless the officers interviewing me demonstrated the correct empathy and rapport, as taught in their training. To this end, instructive posters with such words as Probe, Summarise, Link and, of course, Empathy and Rapport, were stuck all over the walls of the teaching room.

It was here, too, that stooges and trainee officers could sit and watch the mock-interviews being conducted elsewhere in the building, via a closed-circuit television link. I offered up a silent prayer of thanks that I had not been given the role assigned to stooge number one: he had been nicked for stealing a pair of women's knickers from a lingerie store and was now confessing his transvestite urges to a pair of commiserating PCs, while the rest of the coppers, watching on the link, brayed with laughter.

My own story was one of baffling implausibility: despite being a friend of the chief superintendent at Golders Green police station and the chairman of the Avenue Residents' Association, the other Friday morning (1.30am to be precise) I had gone round to my neighbour's house, tipped a can of corrosive brake fluid over his car (rather a nice Jensen), ripped out the stereo and smashed it up with a hammer. Then I'd chucked the can of brake fluid into my dustbin and gone back to bed.

Why? Because the swine (a night-club owner) persisted in having all-night raves in his large, expensive house and the police were unable to stop him. I did it in a moment of blind, frustrated rage.

I spent much of the day sitting in Tottenham Court Road police station, willing myself to commit these details to memory, while being violently distracted by another stooge on the closed-circuit television. He had apparently put his fist through someone's door and was now refusing to play ball with his interlocutors.

'He should have confessed by now,' said one of the watching coppers. 'He's thrown his script out of the window,' said another, as the accused swore and ranted in the interview room and the PCs with him grimly struggled to maintain rapport. 'I'm trying,' said one in desperation, after three-quarters of an hour of stonewalling, 'to empathise with you.' But not even the use of the key word empathise was enough to stem the stooge's rage.

It pointed up, however, the great dilemma of being a stooge. The coppers have to be rewarded for taking the right approach - sympathetic, understanding, relaxed and so on. But for this to happen, the stooge basically has to follow a script and repress all the cussedness, irrationality and bile that he might understandably feel in a police interview.

So what is the interview meant to be? A reward for having taken on board the lessons of the course? Or a serious attempt to put theory into practice under realistic conditions? Still deliberating whether or not to play it rough, I was led off to the interrogation by a policeman wearing black leather jackboots and carrying a gun. ('Nice touch,' the boys said afterwards. 'Made it a bit more special.') I found myself in a cream-coloured room with two very large young men, both apparently dressed for a formal drinks party: lightweight suit the one, blazer and club tie the other. They were polite but friendly and asked if I wanted the interview conducted on first-name terms. I didn't, but this made no difference to their desire to start building some rapport.

'Do you have any hobbies, Mr Jennings?' asked one of them, looking at me thoughtfully. 'How are your children getting on at school?' asked the other. 'We're sorry to trouble you like this, but a serious offence has been reported.' It was surreal: sitting around under the bright lights, passing the time of day like passengers on an aircraft, while at the same time striving to recall my name, personal characteristics and the details of the script, which instructed me to look out for key moments of empathy, before giving in and confessing to the crime.

'A friend of mine,' broke in the first policeman, reviving the cocktail-party ambience, 'restored a classic MG a few years ago. I gather you're interested in cars.'

My mind lurched at this: clearly this was some reference to the Jensen I had vandalised the night before. Or was I really a car buff and this was just small talk, designed to put me at my ease? It was a bluff: the friendly policeman in the blazer and club tie suddenly revealed that one of my neighbours had seen me go out in my pyjamas and dressing-gown and have a go at the car next door.

I wondered whether this was the moment to bring up my friendship with the chief superintendent of Golders Green police station, but I knew that I couldn't mention the topic without lapsing into hysterical giggles - so, instead, I came over all sullen, doing my best to look like a middle-class blagger on The Bill who has been caught with his hands in the company accounts.

It didn't work. I tripped myself up on some detail about my spectacles - and they had me. 'Would you like to tell us what happened?' asked the one in the lightweight suit, tenderly. It was with an intoxicating mixture of shame and relief that I abased myself before my captors and started to babble on about the satisfaction that wrecking the car had brought me . . .

Everyone seemed very pleased with the result. My body language had, apparently, been 'a dead giveaway', while the trick question with the glasses had been handled 'just right'. I had, of course, played a straight hand, giving in on cue and not straying from the storyline, except for occasional moments of amnesia. But how I wish I could have been like the man who broke his neighbour's door and blustered for more than an hour - a masterpiece of fabrication. Now that would have been something to tell the chief superintendent.