Duffer’s Fortnight is apparently the magical times that even a duffer can catch monster trout. But having the right Mayfly kit certainly helps. So take Charles Rangeley-Wilson’s Mayfly MOT to ensure you have everything you need to suceed.

For more on the Mayfly, it’s important to know when to cast and when to stay calm. Follow our advice, read how to catch big trout: monster munchers. And if you are adding to your bucket list, follow our guide to the top 10 trout rivers.

MAYFLY KIT

It’s known as Duffer’s Fortnight because, for a blessed window of time between mid May and early June, the allegedly educated trout of the English chalkstreams become so easy even a duffer can catch them. Despite a long trawl (upstream, of course), I’ve not found the exact origin of the phrase, though “duffer” comes from the Scots word dowfart, meaning stupid. Fishing writer Chris McCully thinks it started with Charles Cotton, who wrote that “with the green drake [the mayfly] and the stoneflie I do verily believe I could some daies in my life… have given over upon the meer account of satiety of sport.” Easy fish, then.

Avoid overdressed flies, which will get soggy and sink, when you are heading for the chalkstreams this May, opting instead for something soft and fuzzy.

Some disagree valiantly with the parody. Legendary riverkeeper Frank Sawyer said that “time and again the mayfly season had proved wrong the old saying Duffer’s Fortnight”. Author John Waller Hills, too, thought that for every day when the fish “mind neither thick gut, nor bad casting, nor wretched imitations”, there are many more when they are “wonderfully difficult”.

The fishing can be capricious for sure but I think that’s mostly because “rough winds do shake the darling buds of May”. And because there’s only so much trout can fit in their bellies. When they’re full they get torpid, just like people do. Hills thought the fourth and 12th days the best and he wasn’t far out. The days before and between are explained first by bemusement at the size of the platter and later by the belly-pain of gluttony.

May is the time when the flies are larger, the rises more extravagant – and when the big fish come out to play.

Time your foray right, however, and there’s no getting away from it: for a few days each year, if you want to catch a trawler-full, you probably can. Mayfly is the time when the flies are bigger, the rises are more extravagant and the fish really are less discerning. It’s also when the big fish come out to play and that’s what makes mayfly really interesting.

Duffer’s Fortnight may well bring to mind an image of the bumbling beginner on the banks of the Avon, the Wylye, the Kennet or wherever, his hands trembling as he ties on some piece of plughole fluff because the biggest fish in the river is cavorting around in front of him like a girl in an Amsterdam window. But we’ve all been there. I can recall times when I’ve found vast fish feeding with such gloopy abandon my eyelids have started to quiver in nervous anticipation. On 17 May 2016 I broke off a six-pounder and actually chewed the ground to ease the loss. For the occasional angler, there is a lot at stake. And Mayfly is undoubtedly the time when the majority of “occasional” anglers have a dabble for trout.

Use simple monofilament nylon for the leader.

I’m not an occasional anymore, not after 30-odd years of obsessive dry-fly pursuit, but I enjoy hosting friends who are. It’s almost as much fun guiding a friend to a large trout as it is to catch it oneself. Almost. Especially once we’ve ironed out the common flaws that stand in the way of catching that glass-case trout-of-a-lifetime. I’m hoping these occasional-angler friends won’t mind me having noticed, as the seasons come and go, how they do tend to make the same mistakes. Mistakes I made, too, in the distant past. So universal are the flaws and so easy are they to fix, I’ve now evolved a sort of Mayfly MOT for the once-in-a-while trouter, a fit-for-duty checklist that may just help land you a monster.

KITTED OUT

First, the kit: some guests come with none at all and they are the easiest. I lend them mine and we skip a whole hour of faffing about. Some have ancient stuff dug out of the attic, others the best that money can buy. No matter who I’m fishing with, however, those with grandfather’s greenheart or those with a smorgasbord of the brand new, rarely do I start the day with someone who has the right set-up at the most important end of the rod/line continuum: the fish end. It’s either 5ft of 8lb nylon looped on with a half-hitch or, conversely, some snazzy assemblage of space-age gnat’s whisker. Both are rubbish.

Mayfly is all about glass-case trout.

That doyen of Wessex chalkstreams, Richard Slocock, taught me there’s only one acceptable set-up for a dry-fly leader. It can turn a duffer into an expert. It can also turn an expert into more of an expert. The reasons I see it done well so rarely are either because it sounds arcane and people don’t really believe it’s worth the effort or because the material is so cheap to buy no-one bothers to sell it. The Right Stuff is ordinary monofilament nylon. All the rest – copolymer this, fluoro that, double-strength the other, all at eight quid a spool – is no use for dry-fly fishing on tangled, weedy rivers. It’s fragile, it coils up when you so much as look at it, it sinks. Throw it all away and instead buy bog-standard monofilament – and don’t let anyone tell you otherwise, especially if they have a logo on their hat. Monofilament is stretchy, easy to knot, tough as old boots and cheap as them, too. Roll your own leaders using blood-knots in line sizes from 20lb breaking-strain down through 15lb, 12lb, 10lb, 8lb, 6lb, 5lb and 4lb, about 12in per section until you get to the last two, which can be 2ft and then finally 3ft long. Roll-your-owns are best but if you’re lazy buy a tapered leader that ends at 5lb, then tie 3ft of 4lb to the end. It’s the most important piece of kit in dry-fly fishing. Miles, miles, miles more important than the rod.

THE HUMBLE KNOT

Next in order of importance is the humble knot that ties this leader to the fly-line. Amazingly, fly-line makers have started to weld loops onto their snazzy fly-lines. This is like putting a marshmallow on an epée, a plough on a Porsche. Cut the loop off. Never tie a loop-to-loop connection. Never use those godawful braided loop things, either. A loop hinges and cannot convey the energy of the cast properly. Instead, use a darning needle to tie a “nail knot” or, better, a needle to tie a “needle knot”: there are instructional videos for these knots all over the internet. Combined with a tapered leader, a needle or nail knot will transfer the energy of the cast seamlessly all the way to the fly and help it go where you want it to, not somewhere else. Provided you have your casting sorted, that is.

FLY LINES AND RODS

Before we get to that, a quick word on fly-lines and fly-rods. You don’t have to chose between grandfather’s split cane and an overdraft. Sure, you can spend £800 on a fly rod and £80 on a fly-line but you can also get good versions of both for under £100 all in. For the line, you can’t beat that old classic Scientific Anglers’ AirCel. With its steepish, weight-forward taper it will turn over obediently even if your casting is not brilliant and like another great line, the Barrio GT90, it can be bought for normal money.

The reel is the one piece of kit that can come out of grandfather’s chest.

Both these lines cast true to weight, which makes the most important thing of all much simpler: matching the line to a medium-action fly-rod that is 8ft to 8ft 6in and rated for a #4 line. You don’t need anything shorter, longer, heavier or lighter. And since £35 will buy you a perfectly good Shakespeare Agility and £60 a Greys GR20, there’s just no excuse, really, for the 10ft greenheart.

The reel, on the other hand, is the one piece of kit that can happily come out of grandfather’s chest in the attic.

CASTING COUCH

My casting MOT for graduate duffers is simple, if extreme. If you’ve kitted up as discussed you’re halfway home. Now all you have to do is learn not to get in the way. This is what you almost certainly do wrong: you don’t load the rod properly because you try too hard. Because you don’t load the rod properly, you try even harder. You make too many false casts (scaring the fish) and when it comes to the final chuck you throw your arm forward, break your wrist too early and snap your elbow straight, as if that will help. It doesn’t. None of this strain and effort helps. It is why your cast doesn’t go anywhere.

Strap the forefinger of your casting hand against the rod to help you to feel what the rod is doing. It will help you to perfect your cast.

To exorcise this casting malaise, I prescribe the following medicine: take your fly rod into the garden, stick your elbow into the space under your ribs and wrap a belt around your chest and bicep. Strap the butt of the fly rod to your wrist with fat elastic bands. Strap the forefinger of your casting hand against the rod, pointing up not around the cork. It is hard to unfold your wrist, or even go too far back with your forefinger and wrist like this. It also helps you feel what the rod is doing. Stand with your back against a hedge. Now cast: you can’t throw your arm, or let your wrist un-cock and you can’t go beyond one o’clock. Notice the rod working more than you? Notice that the line lands straight? That’s all there is to it. You’ve become a lever, not a windmill.

Finally, there’s the fly. Of course, in Mayfly a piece of old carpet will do, even if that might kill the romance. Conversely, most shop-bought mayflies are massively overdressed: they spin the leader in piggy-tail coils, get soggy and sink. Tie your own is my advice but, like you, I often can’t be bothered. So shop bought it is: in which case think soft and fuzzy, and don’t be tempted by the toy aeroplanes.