But I'm getting ahead of myself. Let's get back to Ulan Bator, where I'd arrived after a hellish 28 hours on a train from Beijing, and where I met the man who'd set up my trip who now informed me that the river was a 12-hour ride away aboard a UAZ, a Soviet-built jeep, over dirt roads. Nevertheless, though, he told me, a full staff awaited me at camp.

It was then that I made a terminal error. "Maybe I should take up a few beers for the lads" I said.

Uh, no, I was told. Vodka was what they mostly drank.

"Fine" I said, "a couple of bottles of vodka then"

"Ah, well, a case of two might be better" the man said.

I was a little taken aback until I discovered that the favourite local brand - retailing as Genghis Khan Vodka - cost about 50p a bottle. It was, I'd discover later, maybe the only booze in the world that lived up to its name, as ruthless and destructive as the great Mongolian warrior himself. Also that it came with foil caps that couldn't be replaced

So, "Go ahead" I said, and, as we rolled out of town next morning, we hauled a couple of cases of the stuff with my tackle.

The journey - 12 hours over 260 miles of rough track - was so hideous that even now I can't recall it without a shudder. Six times we were hauled out of deep mud by passing trucks - there was no shovel aboard. (Maybe, I thought, it had been left behind to make room for the Genghis Khan.) Towards the end of the long day, though, we crossed a bridge over the Geroo, the big taimen river I was targeting. It was big, all right - big, and chocolate brown with logs swirling down it, in full flood.

Actually, and naively, I wasn't fazed by this. Brought up on the sea trout rivers of West Wales I was programmed to be pleased by big water. In a couple of days, I thought, the Geroo would be perfect, still high but just tinged with colour. I rubbed my hands with anticipation. Probably it was starting to drop already. I suggested as much to the agent. "It will start to drop" he told me, "about next November. We'll go higher up, to the Khuder"

We hit camp, unloaded. And, I had to say, it looked great - yurts, the traditional felt tents, to sleep in, and spits over open fires for cooking. (I knew a little about Mongolian cuisine already. In Beijing I'd asked a girl I met whether I should take chopsticks or a fork with me. "Neither" she said. "All Mongolians are born with ten chopsticks")

That would prove true, but first we headed to this new river, the Khuder, to check it out. It was clear all right, but, compared with the Garoo, it was a brook. Slowly the truth filtered out. This was no taimen river, though there might be a couple or three small ones in it. The big taimen I was after were in the bigger rivers at lower altitude. And those were unfishable.

We headed back to camp. It looked like a lost cause, but I couldn't have forecast quite how lost it would be. The minute the camp staff saw the Genghis Khan being unloaded, I'd realise later, the trip was doomed

Early that first evening, my crew got to work on the vodka, and I drank with them until I realised that I was out of my class and retreated to my yurt - not, for hours, to sleep: the carousing prevented that. But finally, at some appalling hour, it seemed to fade, and I faded out as well.

And, at sun-up, as I lay in my yurt and contemplated what to do next, peace still reigned. As well it might have done, because when I peered out I realised that I was alone in camp. The staff had left, together with the jeep, and around the dead fire were the empty Genghis Khan bottles. The lads, evidently, had headed off to look for more, and when they would return was a matter for serious doubt.

So what to do? Thoughtfully, they'd left me some food - bread and chunks of cold mutton - and of course I had my ten chopsticks to hand. I breakfasted, thought, put on my waders, grabbed a couple of rods and commenced to walk the marshy mile or two to the Khuder. Fishy but small, was my verdict when I got to it. I decided on a swift reconnaissance with the outfit that I'd choose if some river god ordained that it was catch fish or starve: fixed-spool reel (I'd lived in the US long enough to call it a spinning reel by this time) 6lb test, seven foot spinning rod to throw up to a half-ounce. And a box of blue and silver Mepps, sizes 1 to 4.

And by heaven did it work. Almost every other cast I was hit by lenok - body of a trout but with a sort of barbel-shaped snout - running up, I guess to around 5 lbs. They were fun, but, after a while, much too easy. I quit after a couple of hours and headed back to camp for a fly rod: I'd see how the lenok rated on a 6-weight.

Back on the banks of the Khuder I tied on any old wet fly - I hardly looked at it - and started casting. There was a first-time take. Another lenok, naturally. But no: this was a lovely, back-pedalling grayling. I netted it - a couple of pounds. Soon I'd forgotten my treacherous camp staff and the Genghis Khan vodka, I was having the best grayling day of my life and I took another look at the fly that they were falling for. It was a #12 Blue Charm I now recalled buying in the little tackle shop in Ballina, Co Mayo at the end of the bridge over the Moy. It had been great for grilse in very low water on the Ridge Pool.

I looked up at the Mongolian sky at what I'd put down in my early frustration as bloody vultures. They were not. They were Imperial Eagles, a dozen of them, soaring over the river, a sight to kill for.

Well , I suppose, I've ended up with a bit of fishing pornography after all. There's just one footnote. Two days later my abashed crew returned with the jeep and I climbed aboard it to head back to Ulan Bator.

I didn't tip the sods.