Hills' classic work and perhaps the best book on chalk stream fishing ever written. Definitely worth a read, as is almost anything by the author, and my advice is to reserve it until you have a long winter weekend facing you, with the wind howling and the rain rattling on the windows. Then sit yourself down with a whisky to hand and let Hills transport you back to the halcyon days of the twenties.

'But it was now past six o'clock: and the spent fly began to come on the water. All over the surface mayflies were to be seen; they were in clouds in the air above, busy egg-laying, now dipping down and just touching the top of the stream, then rising in the air, then dipping again. They got thicker and thicker, and so did the bodies of dead mayflies floating down. If your eye followed an individual egg-layer, you noticed, if you could pick her out from the swarms of her companions, that her trips through the air got shorter, and her her visits to the water more frequent, and that, instead of just brushing the surface in order to lay her eggs, she began to sit for a second or so upon it, until the time came when she could rise no more. Then, her work done, her store of six or seven thousand eggs safely laid, the future of her race assured, she settled on the surface and sailed down upright; but soon she would give a shiver, one of her wings would collapse on the water, until finally she died and fell flat, wings extended in the form of the cross. Thicker and thicker grew the mass of fly over the water, more and more numerous those carried down by the current. At first those floating were present in all stages, sitting upright, or half-collapsed, or dying, or dead: but soon the dead predominating, until all that could be seen were their bodies, the dead fly, the spent gnat. These came down in ever increasing quantities. In the backwaters and eddies they were packed nearly solid. In the main current, the quick swinging stream of the lower Test, they were separated only by inches. All the broad river was covered, and bore them seawards like a moving carrier. Now all these had escaped the attacks of trout and grayling, and the swifts and swallows and wagtails and warblers and chaffinches and many other birds which prey upon them: all of them had escaped, and had reproduced their species : when you looked at the countless thousands which floated down in the small time during which you saw only a small part of the river, you realised that the quantities of them which had survived were so vast that the assaults of all their enemies made no appreciable impression on their number.'

That's what I call a hatch. Magical book.