I walked round to the front of the building, distinguishable from the back only by the double doors. I entered a cheerless foyer with a security booth and banks of stainless-steel lift doors. The Scouse security officers were as efficient as if they'd been privatized. Name and purpose of visit, who visiting, where car parked, car registration number. Then they note your arrival time and issue a security pass. If I were a dedicated hacker, I could see half a dozen ways to get my hands on one of their terminals.

Again, I restrained my more piratical instincts and went across the hall to Inquiries. It was like a dentist's waiting room, complete with year-old magazines sitting on a low table. The chairs were the cloth-upholstered sort two grades up from those hideous orange plastic ones you get down the Social Security. Everything was a bit scuffed, as if it was last redecorated before Thatcher came to power. I walked over to a high counter in the corner of the room. It was empty except for a cash register and a computer monitor and keyboard. I craned my neck round to read 'Welcome to the Land Registry Computer System' in amber letters on the black screen.

The sign on the desk said, 'Please ring for attention'. They obviously brought the sign with them from the old building, since it's probably the only thing in the whole place made of wood. It's certainly the only thing made of wood with gilt lettering on it. I rang the bell and waited for a desiccated old man in a frock coat to shuffle through the door.

That'll teach me to make my mind up in advance of the facts. It took less than a minute for a young woman to appear who, frankly, wasn't my idea of a civil servant. For a start, she wouldn't have looked out of place at one of Richard's gigs in her fashionably baggy Aran sweater and jeans. For another, she looked like she enjoyed her work. And she didn't behave as if having to deal with members of the public was a major pain for her. All very novel.

'I wonder if you can help me,' I said. 'My name's Brannigan, Kate Brannigan. I rang last week with a list of addresses that I needed copies of the register for.'

The woman smiled. 'That's right. It was me you spoke to. I've got the copies ready, if you don't mind waiting a minute?'

'Fine,' I said. As she disappeared back through the door, I allowed myself a grim smile of satisfaction. No doubt this was where the wait began. I helped myself to one of the elderly magazines and sat down. I was only one paragraph into the fascinating tale of a soap star's brush with death on the motorway when she returned with a thick bundle of documents.

'Here you are,” she announced. 'Seven sets of copies of the register. It's not often we get asked for so many, except by conveyancing experts. And in so many different locations,' she added, obviously fishing.

I dumped the magazine and went back to the counter. 'I suppose it made life a lot more complicated for you when they changed the rules to allow anyone to examine any entry in the register,' I parried.

'I don't know about complicated,' she said. 'But it's made it a lot more interesting. I only ever used to talk to solicitors and their secretaries, and occasionally people who wanted copies of their own entries. Now we get all sorts coming in. Often, they want to check the register on their neighbours' properties because they think they might be in breach of some covenant or other, like no caravans, or no garden bonfires. A right lot of Percy Sugdens, some of them are,' she added with a giggle.

She turned to the cash register. I'd taken the precaution of hitting the hole in the wall with the company cashpoint card, so I wasn't flummoxed by her demand any more than she was by my request for a VAT receipt. I made a mental note to ask Shelley to keep a running total of Ted Barlow's account and to bill him as soon as it went five hundred pounds over the retainer he'd given us. I didn't want us to end up working for nothing if I couldn't clear up the scam fast enough to keep his business afloat.

I picked up my copies of the register entries and squeezed them into the back pocket of my handbag. Then, a thought occurred to me. 'I wonder if you could clear something up for me?' I said.

'If I can, I'd be happy to,' the young woman said, giving me a bright smile that appeared to be completely natural. She obviously wasn't destined to last long in the Civil Service.

'What's the actual process here? And how long does it take between details being sent to you and them being entered into the register? I was thinking particularly of land that's being registered for the first time and has then been split into parcels.' If anyone could help me work out Martin Cheetham's role in the double-sale scam, it had to be the Land Registry.

'Right,” she said, dragging the word out into three distinct Scouse syllables. 'What happens is this. Every morning, a Day Listing gets put on the computer. That lists all the title numbers that are the subject of alteration, inquiry, registration or anything else. Once a title number has appeared on the Day Listing, it stays listed until it has been entered into the full register. At any one time there are about 140,000 properties on the Listing, so it takes a little time to get round to them all.'

Suddenly, I began to understand how the Land Registry got its reputation for being as slow as a tortoise on valium. Before they started their computerization, it must have been a nightmare. 'So what sort of time scale are we looking at?' I asked.

'It depends,' she said. 'We've got about half a million records on computer, which has speeded things up a bit, except when the system crashes.'

'So, allowing for that, how long does it take for changes to make their way on to the register?'

'For a change of ownership, we've got it down to about four weeks. A first registration takes about eleven weeks, and for a transfer of part, it's about fifteen weeks,' she said.

Light was beginning to glimmer, very faintly. 'So if someone was registering a piece of land for the first time, then almost immediately registering the division of that land into plots and the sale of those plots, the whole thing could take six months?'

'In theory, yes,' she admitted, looking slightly uncomfortable.

'So if someone tried to sell the same plot twice, they might be able to get away with it?'

She shook her head vehemently. 'Absolutely not. Don't forget, it would be on the Day Listing. As soon as the second purchaser's solicitor instigated a search, they would be told that the file was already active, which would ring alarm bells and put any transaction on hold.'

'I see,' I said, smiling my thanks. 'You've been very helpful.'

'No problem. Any time.' She returned the smile.

I walked back to the car in thoughtful mood. I was pretty convinced now that I knew how Alexis and Chris had been ripped off. The root of the scam lay in the difference between registered and unregistered land. I dredged my memory for all I'd ever learned about land, which wasn't that much, since land comes in the final year of a law-degree course. I suspect that might have been one of the factors in my decision to duck out after my second year. But sometimes, like now, that last year would have come in handy.

The ownership of about a third of the land in the North West of England has never been registered. If you think about it, it's only in relatively recent times that there was any need for registration, when we all became economically and socially mobile, as the academics put it. In the olden days before the Second World War, if you were buying a property or a piece of land, you usually knew the person who was selling it. Probably, they'd been your employer, or had sat in the front pew of the local church all your life. Some form of independent registration only became an issue when you were buying from a stranger and you had no proof of their reputation; they just might not actually own London Bridge, after all. Since the Land Registry really got going in the thirties, most transactions have been registered in what was supposed to be a slow but sure process. Ho, ho.