I spent three hours on the Tongariro River Hydro Pool one evening this week and landed nine trout. One was an excellent fresh-run rainbow hen, three were recovering spawners in pretty good nick and five were the fish I was targeting - fat juveniles up to 1.2kg that fight like angry little bulls on light tackle. All told, I got more than 20 hits.

Three other anglers visited the pool in that time. They were using traditional nymph and wetline techniques but caught nothing - and they were watching me closely.

So what was my secret, what was I using? Nymphs? No. Woolly Buggers? No. Must have been glo-bugs then? No. Well, what else is left - worms? No.

I was using what I consider the most deadly of all flies for evening river fishing, flies that were brought here 140 years ago by the first anglers arriving from England, flies long overlooked since the explosion in nymph fishing relegated most other techniques to the sideline.

I was using the long-forgotten fly: the wonderful wee wet.

I'd been fishing the Hydro during the afternoon with traditional heavy rod, nymphs and lead shot. I noticed, when the irregular chilly breeze dropped to leave mild periods, several fish rising sporadically along the cliff by the right-hand bank, and the swallows were flitting about after hatching mayflies - the ones on TV living life to the full in their 24-hour existence.

I set up a light No 4 rod and tied on a large dry fly - an elk-hair caddis - mainly to use as a strikemarker and tied two wee wets on 5lb fluorocarbon 20cm apart 20cm behind the dry. The hits started within a few casts and they hardly stopped, 95 per cent on the wee wets. Only tiddlers took the caddis off the surface.

As evening came on, the bigger fish were taking and it was a pleasant surprise when the fresh-run hen took a wee wet in shallow riffles where anglers normally wade at the top of the pool. Who said fresh-runners hug the bottom and never feed in the shallows? With the light rod, that fish took me well down the pool in a battle royal.

Many beginners have never heard of a wee wet. It's all nymphs, bombs and globugs as big as bulldozers these days. But those anglers with the years behind them use wee wets with great success.

Some experienced fishers say the wee wet does not represent anything at all. Others say it represents a small, darting fish. Still others say it is an insect emerger struggling to break through the surface film. And me? I reckon it represents a drowned mayfly and I've been fishing for 50 years and reckon I know what I'm talkin' about.

The traditional method of fishing wee wets is across and downstream with a sinking line, mending the line carefully to keep it straight so you can stay in contact with the flies to feel the strikes, which can be savage enough to break the tippet for the unwary dreamer.