In fact we were not able to lie back at all. The aye-aye is a nocturnal animal and does not make daytime appointments. The few aye-ayes that were known to exist in 1985 were to be found (or more usually not found) on a tiny, idyllic, rainforest island called Nosy Mangabe, just off the north-east coast of Madagascar to which they had been removed twenty years earlier. This was their last refuge on earth and no one was allowed to visit the island without special government permission, which Mark had managed to arrange for us. This was where our but was, and this was where we spent night after night thrashing through the rain forest in torrential rain carrying tiny feeble torches (the big powerful ones we'd brought on the plane stayed with the 'surplus' baggage we'd dumped in the Antananarivo Hilton) until... we found the aye-aye.

That was the extraordinary thing. We actually did find the creature. We only caught a glimpse of it for a few seconds, slowly edging its way along a branch a couple of feet above our heads and looking down at us through the rain with a sort of serene incomprehension as to what kind of things we might possibly be, but it was the kind of moment about which it is hard not to feel completely dizzy.

Why?

Because, I realised later, I was a monkey looking at a lemur.

By flying from New York and Paris to Antananarivo by 747 jet, up to Diego-Suarez in an old prop plane, driving to the port of Maroantsetra in an even older truck, crossing to Nosy Mangabe in a boat that was so old and dilapidated that it was almost indistinguishable from driftwood, and finally walking by night into the ancient rain forest, we were almost making a time journey back through all the stages of our experiments in twig technology to the environment from which we had originally ousted the lemurs. And here was one of the very last of them, looking at me with, as I say, serene incomprehension.

The following day Mark and I sat on the steps of the but in the morning sunshine making notes and discussing ideas for the article I would write for the Observer about the expedition. He had explained to me in detail the history of the lemurs and I said that I thought there was an irony to it. Madagascar had been a monkey-free refuge for the lemurs off the coast of mainland Africa, and now Nosy Mangabe had to be a monkey-free refuge off the coast of mainland Madagascar. The refuges were getting smaller and smaller, and the monkeys were already here on this one, sitting making notes about it.

`The difference,' said Mark, `is that the first monkey-free refuge was set up by chance. The second was actually set up by the monkeys.'

'So I suppose it's fair to say that as our intelligence has increased it has given us not only greater power, but also an understanding of the consequences of using that power. It has given us the ability to control our environment, but also the ability to control ourselves.'

°Well, up to a point,' said Mark, `up to a point. There are twenty one species of lemur on Madagascar now, of which the aye-aye is thought to be the rarest, which just means that it's the one that's currently closest to the edge. At one time there were over forty. Nearly half of them have been pushed over the edge already. And that's just the lemurs. Virtually everything that lives in the Madagascan rain forest doesn't live anywhere else at all, and there's only about ten per cent of that left. And that's just Madagascar. Have you ever been to mainland Africa?

No.

`One species after another is on the way out. And they're really major animals. There are less than twenty northern white rhino left, and there's a desperate battle going on to save them from the poachers. They're in Zaire. And the mountain gorillas, too -they're one of man's closest living relatives, but we've almost killed them off' this century. But it's happening throughout the rest of the world as well. Do you know about the kakapo?'

`The what?'

`The kakapo. It's the world's largest, fattest and least-able-to-fly parrot. It lives in New Zealand. It's the strangest bird I know of and will probably be as famous as the dodo if it goes extinct.'

`How many of them are there??

'Forty and falling. Do you know about the Yangtze river dolphin?

No.

`The Komodo dragon? The Rodrigues fruitbat?'

'Wait a minute, wait a minute,' I said. I went into the but and rummaged around in the ants for one of the monkey's most prized achievements. It consisted of a lot of twigs mashed up to a pulp and flattened out into sheets and then held together with something that had previously held a cow together. I took my Filofax outside and flipped through it while the sun streamed through the trees behind me from which some ruffed lemurs were calling to each other.

`Well,' I said, sitting down on the step again, 'I've just got a couple of novels to write, but, er, what are you doing in 1988?

The first animal we went to look for, three years later, was the Komodo dragon lizard. This was an animal, like most of the animals we were going to see, about which I knew very little. What little I did know was hard to like.

They are man-eaters. That is not so bad in itself. Lions and tigers are man-eaters, and though we may be intensely wary of them and treat them with respectful fear we nevertheless have an instinctive admiration for them. We don't actually like to be eaten by them, but we don't resent the very idea. The reason, probably, is that we are mammals and so are they. There's a kind of unreconstructed species prejudice at work: a lion is one of us but a lizard is not. And neither, for that matter is a fish, which is why we have such an unholy terror of sharks.

The Komodo lizards are also big. Very big. There's one on Komodo at the moment which is over twelve feet long and stands about a yard high, which you can't help but feel is entirely the wrong size for a lizard to be, particularly if it's a man-eater and you're about to go and share an island with it.

Though they are man-eaters they don't get to eat man very often, and more generally their diet consists of goats, pigs and deer and such like, but they will only kill these animals if they can't find something that's dead already, because they are, at heart, scavengers. They like their meat bad and smelly. We don't like our meat like that and tend to be leery of things that do. I was definitely leery of these lizards.

Mark had spent part of the intervening three years planning and researching the expeditions we were to make, writing letters, telephoning, but most often telexing to naturalists working in the field in remote parts of the world, organising schedules, letters of introduction and maps. He also arranged all the visas, flights and boats and accommodation, and then had to arrange them all over again when it turned out that I hadn't quite finished the novels yet.

At last they were done. I left my house in the hands of the builders, who claimed they only had three more weeks' work to do, and set off to fulfil my one last commitment - an author tour of Australia. I'm always very sympathetic when I hear people complaining that all they ever get on television or radio chat shows is authors honking on about their latest book. It does, on the other hand, get us out of the house and spare our families the trial of hearing us honking on about our latest book.

Finally that, too, was over and we could start looking for giant lizards.

We met up in a hotel room in Melbourne and examined our array of expeditionary equipment. 'We' were Mark, myself and Gaynor Shutte, a radio producer who was going to be recording our exploits for the BBC. Our equipment was a vast array of cameras, tape recorders, tents, sleeping bags, medical supplies, mosquito coils, unidentifiable things made of canvas and nylon with metal eyelets and plastic hooks, cagoules, boots, penknives, torches and a cricket bat.