Megan Boyd became famous in her lifetime as a tyer of the most beautiful and effective salmon flies. She died at a nursing home in Golspie in 2001 but was born again recently in the film Kiss the Water, a documentary about her life and the bewitching flies she tied at a desk in her small cottage near Brora.

Boyd was not a native Scot. She moved to Scotland when she was a teenager and her father took a job as keeper on an estate in Sutherland. A fellow keeper, Bob Trussler, taught young Megan how to tie by disassembling finished flies only for her to tie them again. Once she started, such was her talent and passion, she never stopped. She moved into her own cottage aged 20 and there, dressed in heavy work boots, a shirt and tie, she tied flies for 53 years, preferring to work for locals who left their orders under her door-mat. But as her reputation grew she tied for more glamorous clients as well, such as The Prince of Wales. She cut her own hair, too. And she lived without running water, without a television or, indeed, electricity. She stopped only when her eyesight failed her and she noticed that the heads on her flies were becoming too big. “Once you start to do that,” she said, “it’s no use.”

The romance of Boyd’s life – the croft, the eccentric clothes, the breathtaking feathery creations and her Royal fans – caught the eye of the American movie director Eric Steel when he read her obituary in the New York Times. It played hauntingly on his imagination for almost a decade until, finally, he succumbed – like the anglers and salmon that had succumbed to her flies – and rose to capture it in film. He travelled to Brora, interviewed the people who knew her and crafted from those tapes – and lingering shots of the Scottish landscape – a documentary about her life.

Boyd’s flies, by all accounts, had a certain something about them, a rare perfection or beauty or magnetism, that salmon found ir-resistible. It’s a lovely idea, that fish might be attracted to a fly because of some special quality in the feathers or imparted by its artist cre-ator. I was once sold a particularly beautiful selection of dry flies in the Dordogne tied with feathers whose sheen, so I was told, derived from the uniquely pure air of that region and gave to the flies a quality that trout found irresistible. Dordogne trout, so it proved, find more or less every fly resistible, and these were no exception: untroubled by fish they have joined a selection of special flies I have built up over the years from Slovenia, Croatia, Japan, each one donated with a breathless allusion to its magic.

And then you go and catch the wiliest of fish with a feather plucked from the arse of a scruffy old duck. As for salmon, the more I angle for these capricious fish, the more I suspect that it makes no difference what flies you use, how well tied they are, how small are their heads. Or even whether they are magic.

Eric Steel isn’t a salmon angler, you see. And it makes Boyd’s flies no less beautiful to know that she wasn’t a salmon angler, either. Maybe it makes them more beautiful. Because Boyd’s wondrous feathery hooks were works of artistic craft that – in terms of catching animate creatures – had a much more quan-titative effect on anglers than salmon.

Such is the way with salmon flies. Maybe it is the whole point of them: that they should catch a man first and be beautiful. The cast is beautiful. The swing of the fly, the mend, the take, the fight, the fish and the setting: these things are all beautiful. The whole baroque pursuit is beautiful. Is it any wonder we get carried away with the flies? We can tell ourselves that this beauty makes a difference to the fish. But it doesn’t. A hook with silver foil from a chocolate bar wrapped round it will take a salmon if that fish is in the mood. I once caught 14 salmon in a droughty week using chocolate-bar tinsel as the main ingredient of my hideous creation: a made-up pattern I tied a few beers downwind and called Flash Gordon because it reminded me of the tinselly sparks coming out the back of Flash’s Fifties space rocket. My plan was to try something tiny but highly visible and it worked. But then another angler caught his fish on the biggest Sunray Shadow you’ve ever seen. So what do you know?

I’m not saying a given salmon will take any fly. Sometimes a fish will disdain a whole boxful  of flies only to take the umpteenth pattern you show it, some fly you’d forgotten existed and that seems to your untrained, unfishy eye to be no better than any of the others.

I remember the River Morsgail a few summers back, dry as a bone and more or less hopeless, the river leaking from the moor under a burning, summer sky and me staggering down to it in my slippers determined to fish after an irritating minor operation that was far more painful than advertised. Three or four times in that week and against all the odds I saw a fish move to my fly. And I caught none of them on the fly they first moved to. They turned to a salmon fly but I caught them on a goldhead Prince Nymph left over from some Patagonian sea-trout exploration, a dry caddis that had last caught a trout in a chalkstream on a hot summer evening, and a Muddler Minnow that normally saw service at Chew Valley Lake in October.

I remember the River Coquet, also in a drought, and lethargically casting my line over a deep, slow and utterly fishless pool alongside the walls of an old priory. There was little point but it was fishing. Then the priory’s owner arrived and started to clatter about in the river with a ladder, clambering up and down to pull ragwort from the ancient walls, and with that racket the pool morphed into fishy life. A dozen salmon loomed from the depths and swam about in circles as if to suggest that someone really ought to keep the noise down. One of them rose in the water, kept on rising and came within an inch of my fly before disappearing, without turning so much as a ripple on the surface. I changed the fly again and again, and each change provoked one curious enquiry. Finally, I changed down to something tiny and up the fish came and engulfed it.

And then, last summer, on one of those long, flat pools one can only fish in a gale, a large cock fish moved to – but would not take – a fly box of different salmon flies. The Icelandic guide at my shoulder delved into his selection (it was, after all, a big fish) and we went through those, too: those weird Francis patterns that look like hairy pessaries, micro coneheads, micro hitch-patterns of various sorts, the works. The salmon turned once at every single fly we showed it. In despair I considered the flies hooked into the lapel of my wading jacket and plucked from that selection of knackered lures a buzzer pattern tied for Lough Corrib’s duckfly hatch. The fish took that fly hard first chuck, more or less as soon as my cast hit the water.

So no, I’m not saying a given salmon will take any fly. I’m saying that the fly any given salmon may take could be any fly. Or only one. Or none. In the words of Miss Anne Elk, whose theory it was that all brontosauruses were thin at one end, much, much thicker in the middle and then thin again at the far end, “My theory, that belongs to me, is as follows…” If the salmon you are casting to doesn’t take the fly you have on, then it might take a different one. That is all that can be said on the matter. Almost.

Of course, I’ve been tempted to try to find some pattern in the random chaos of the Atlantic salmon’s appetites. This is what we all do. This is all anyone is doing attributing magic qualities to the mesmeric creations of Megan Boyd. Angling is, after all, either a low form of science or religion. Whether I’m empirical or superstitious I couldn’t say, but compelled to confound my own theory by stating a preference for one pattern over any other, well I’d have to choose… a Cascade.

They are a bit foppish and dandy, salmon flies. Most have long, curly locks and stand at a jaunty angle, twinkling. But if Marc Bolan had been a salmon fly, he’d have been a Cascade. It’s the solid-gold, easy-action glam rocker of salmon flies. A weird pick, perhaps, given that the Cascade did not take any of the fish des-cribed above, given that it takes maybe only a quarter of the salmon I catch. But that’s be-cause only a quarter of the salmon I catch take first time. It was a Cascade that turned those fish first time. And I knew they had turned because a Cascade shines through the water like a blowtorch. It is easy to see where it is and easy to see if anything moves near it. Once you know the fickle, finny feckers are there, well, the battle is half over. Then you can bother them with all the creations in your fly box. And, chances are, they’ll take one eventually.

I wonder whether Megan Boyd, who, it cannot be denied, was something of a doppelganger for Dave Hill of Slade, ever tied a Cascade? That would be a fly worth having.