I sighed mentally. 'How long had you known Mrs. Robinson?' I asked.

'Well, she only moved in in December,' the woman said. 'She was hardly here at all that first month, what with Christmas and everything. Most weeks she was away three or four nights. And she was always out during the day. She often didn't get home till gone eight. Then she moved out a couple of days after the conservatory went. My husband said she probably had to move suddenly, on account of her work, and maybe took the conservatory with her to a new house.'

'Her work?'

'She told my Harry that she was a freelance computer expert. It takes her all over the world, you know. She said that's why she'd always rented the house out. There's been a string of tenants in there ever since we moved in five years ago. She told Harry this was the first time she'd actually had the chance to live in the house herself.' There was a note of pride in her voice that her Harry had managed to get so much out of their mysterious neighbour.

'Can you describe her to me, Mrs.-?'

She considered. 'Green. Carole Green, with an e, on the Carole, not the Green. Well, she was taller than you.' Not hard. Five three isn't exactly Amazonian. 'Not much, though. Late twenties, I'd say. She had dark brown hair, in a full page-boy, really thick and glossy her hair was. Always nicely made up.

And she was a nice dresser, you never saw her scruffy.'

'And the man you mentioned?'

'There was more than one, you know. Most nights when she was here, a car would pull up in the garage later on, about eleven. A couple of times, I saw them drive off the next morning. The first one had a blue Sierra, but he only lasted a couple of weeks. The next one had a silver Vauxhall Cavalier.' She seemed very positive about the cars and I commented on it. 'My Harry's in the motor trade,' she informed me. 'I might not have noticed the men, but I noticed the cars.'

'And you haven't seen her since she moved out?'

The woman shook her head. 'Not hide nor hair. Then the house was rented out again a fortnight after she moved. A young couple, just moved up from Kent. They left a month ago, bought a place of their own over towards Widnes. Lovely couple, they were. Don and Diane. Beautiful baby girl, Danni.'

I almost pitied them. I bet they'd not thought fast enough to get out of the little social events of the Grove. I couldn't think of anything else to ask, so I made my excuses and left. I considered trying the other neighbours, but I didn't see how anyone could have succeeded where Carole with an e had failed.

Scarborough Walk was only a mile away as the crow flies. Clearly the crow has never inspired a town planner. Only a Minotaur fresh from the Cretan labyrinth would feel at home in the newer parts of Warrington. I negotiated yet another roundabout with my street map on my knees and entered yet another new development. Whitby Way encircled a dozen Walks, Closes and Groves like the covered wagons pulled up to repel the Indians. It was about as hard to breach. Eventually, second time round, I spotted the entrance to the development. Cleverly designed to look like a dead end, in fact it led straight into a maze that I managed to unravel by driving at 10 m.p.h. with one eye on the map. Sometimes I wonder how I cope with a job as glamorous, exciting and risky as this.

Again, there was no conservatory. The couple who lived there now had only been renting it for a couple of months, so the harried mother with the hyperactive toddler wasn't able to tell me anything about the people who'd actually bought the conservatory. But the woman next door but one had missed her way. She should have been on the News of the World's investigative desk. By the time I escaped, I knew more than I could ever have dreamed possible about the inhabitants of Scarborough Walk. I even knew about the two couples who had moved out in 1988 after their wife-swapping had turned into a permanent transfer. However, I didn't know much about the former inhabitants of number six. They'd bought the house the previous November, and had moved out at the end of February because he'd got a job out in the Middle East somewhere and she'd gone with him. She'd been a nurse on permanent night duty, at one of the Liverpool hospitals, she thought. He'd been something in personnel. She'd had a blonde urchin cut, just like that Sally Webster on Coronation Street. He'd been tall, dark and handsome. She'd had some kind of little car, he'd had some kind of big car. He often worked late. They went out a lot when they weren't working. The perfect description to put out to Interpol.

The next house still had its conservatory. It also still had a satisfied customer, which I was grateful for. I really didn't need to be mistaken for the customer services department of Colonial Conservatories. I ploughed on through the list, and when I reached the end, I reckoned I was entitled to a treat for having spent so task-orientated a day. Four o'clock and I was back in Manchester, sitting in my favourite curry shop in Strangeways, tucking into a bowl of karahi lamb.

As I scoffed, I popped the earpiece of my miniature tape recorder in place and played back the verbal notes I'd made after each of my visits. Five out of the eight were victims of MCS (Missing Conservatory Syndrome, I'd christened it). The only common factor I could isolate was that, in each case, the couple concerned had only lived in the house for a few months after buying it, then they'd moved out and let the place via an agency. I couldn't make sense of it at all. Who were all these people? Two brunettes, one auburn, two blondes. Two with glasses, three without. All working women. Two drove red Fiestas, one went everywhere by taxi, one drove a white Metro, one drove 'something small'. All the men were on the tall side and dark, ranging from 'handsome' to 'nowt special'. A description that would cover about half the male population. Again, two wore glasses, three didn't. They all drove standard businessmen's cars – a couple had metallic Cavaliers, one had a red Sierra, one had a blue Sierra, one changed his car from 'a big red one' to 'a big white one'. Not a single lead as to the whereabouts of any of them.

I had to admit I was completely baffled. I dictated my virtually non-existent conclusions, then checked in with Shelley. I answered half a dozen queries, discovered there was nothing urgent waiting for me, so I hit the supermarket. I fancied some more treats to reward me for the ironing pile that faced me at home. I had no intention of including myself in Richard's plans for the evening. I can think of more pleasurable ways of getting hearing damage than boogying on down to a double wicked hip hop rap band from Mostyn called PMT, or something similar. There's nothing like a quiet night in.

And that’s exactly what I got. Nothing like a quiet night in. I'd gone back to the office after a quick hit on Sainsbury's and dropped off my cassette for Shelley to input in the morning. I was sure the thought that it was for Ted Barlow would make her fingers fly. Then I'd finally managed to find the peace and quiet to develop my surveillance films from PharmAce Supplies. As I stared at the film, I wished I hadn't. On the other hand, if you're going to have a major downer, I suppose it's as well to have it at the end of a day that's already been less than wonderful, rather than spoil a perfectly good one.

Where there ought to have been identifiable images of PharmAce's senior lab technician slipping in and out of the building in the middle of the night (timing superimposed on the pictures by my super-duper Nikon), there was only a foggy blur. Something had gone badly wrong. Since the commonest cause of fogged film is a camera problem, what I then had to do was to run a film through the camera I'd been using that night, and develop it to see if I could pinpoint the problem. That took another hour, and all it demonstrated was that there was nothing wrong with the camera. Which left either a faulty film or human error. And the chances were, whether I liked it or not, that human error was the reason. Which meant I was stuck with the prospect of another Saturday night in the back of the van with my eye glued to a long lens. Sometimes I really do wonder if I did the right thing when I gave up my law degree after the second year to come and work with Bill. Then I look at what my former fellow students are doing now, and I begin to be grateful I made the jump.