Roger Beck is a big, burly, bearded Yorkshireman. But put him by a river with a fly rod in his hand and a pair of waders on his legs and he can move with the grace of a dancer. Down on the River Rye, a swift, swirling stretch of water that cuts through the rough meadows and gullies of north Yorkshire, he is obviously at home. “Look, see, there’s a rise! See there, that’s a mayfly, that’s a yellow sally (another sort of fly).” I can see none of these things, but then Roger Beck spends hours of every week by or in the water, casting his line in swift, graceful rolls to land the fly in just the spot where the trout are most likely to bite.

As a qualified national instructor for the Salmon and Trout Association, he is much in demand as a fly-casting tutor and (paid) fishing companion. “Last week I was somebody’s birthday present,” he says. “In a couple of weeks I’m somebody’s wedding anniversary present. I don’t know what that says about their marriage.”

It’s the de-stressing quality of fly fishing, as much as improving chances of landing a weighty catch, that Roger Beck is interested in promoting. And he should know. Fishing, he says, saved his bacon. When he was an overworked, overwrought deputy head in a York secondary, teetering on the edge of a breakdown, it was the peace and solitude of the sport, the absorbing sights and harmonious sounds of life by water, the concentration needed to draw the trout, that kept body and soul together. He now wants others to enjoy its benefits.

Earlier this year he approached the Institute of Managers, in response to its report on the damaging effects of stress on the performance of middle and senior managers. He has also offered his services to the police and the fire service. And since becoming a qualified fly-fishing instructor and setting up his business, Beckfisher, he has been approached by other teachers, men and women, wishing to take up the sport for relaxation, as well as by those approaching retirement.

The popular image of a fly fisher is someone in twill and green wellies, well heeled, most probably landed and most definitely male. The truth, says Roger Beck, is a little different. You can be kitted out and on the water, permit in hand, for less than pound;100. “It’s the skill, not the rod that catches the fish,” he says. Neither is there a need for male strength. Fishing has more to do with precision, timing and finesse. “Women are usually very good. It’s not brute force but timing, care and technique that’s going to get that bit of fluff (the fly) over there precisely where you want it to be.”

Roger Beck was deputy head of his secondary for 14 years. He’d gradually become aware that the workload and way he was required to manage was making him ill. In 1990 he was off work for three months with “reactive depression”, and finally retired because of ill health last year, aged 51. The cause, he says, was the “nonsense of a job description you cannot fulfil”. A fellow deputy had retired and was not replaced “so I got a big slice of his job on top of mine”.

It was the lack of time for colleagues which he found hardest to take. “I always believed it was worth spending the time to create an environment where people wanted to do things for you. That may take longer, and county hall may be jumping up and down for those returns, but it means the needs of youngsters are met. If you don’t have the goodwill of teachers, pupils miss out on so much because the talents and skills teachers have beyond heir qualifications cannot be mobilised.

“I found the grimaces and the sighs from staff becoming more heartfelt, despite my best efforts. The goodwill was becoming harder and harder to retain because of the workload.”

An Ofsted inspection in 1995 made matters worse. “In the months before, I had to watch people who were talented, successful or perfectly competent lose confidence. People who cared enormously began to indulge in self-doubt, and the doubt turned to fear as the inspection drew closer. The school got a good report, but as a senior manager I didn’t learn anything I didn’t already know. It was all so unnecessary.”

Roger Beck believes it was his “unassailable” Friday night fishing sessions that kept him going for as long as he did. There was an unwritten rule that “as soon as Roger finishes on a Friday he goes fishing, and nobody - not even the head - should be foolish enough to get in the way of that”. He says: “You go to a beautiful place where there are no harsh sounds and you become absorbed in the task in hand. The very nature of the sport means you cannot rush it - if you do, it doesn’t work. Physically it makes you slow down and mentally it helps you get a lot of rubbish out of your head.”

He had a health scare - a query over bowel cancer, which proved negative but which had led to exploratory surgery - and when the pace of work became so frenetic that “people were shoving notes under the toilet door”, he finally cracked. “I would drive to school and I would sit there in the car park willing myself to get out,” he says. “Finally, I couldn’t.”

He spent three months sitting in his garden “watching weeds grow”. It was the fishing that brought him back to health. “Because it is so absorbing you are not consciously addressing issues. But on the way home you will find that things are more in perspective, that you have mentally filed things away in the right place.”

He now offers teaching sessions by the river or the lake, advising beginners on basic equipment, casts, playing and landing a fish, practice exercises and safety issues. For those with experience, the teaching becomes much more technical - distance casting, dealing with difficult wind conditions and restricted space, for example. He teaches how to make flies (fly tie) and how to identify the flies and other creatures on which the fish feed.

Roger Beck grew up in Kiverton Park, a south Yorkshire mining village. He went coarse fishing most Sundays with his dad and uncles, cycling 10 to 15 miles in the early mornings with his tackle and umbrella on his back. Fishing was an “escape” from the pit villages, but in those days none of his friends and relatives went fly fishing. That was definitely out of their class. The nearest trout would have been on the Derbyshire Wye, and that was “out of the question” in terms of distance and cost.

He discovered the joys of fishing with fly during his first job teaching biology in Cumbria. It wasn’t nearly as expensive as he had imagined and it took him to some beautiful sites. He now fishes all year round, taking up the fly when the coarse fishing season packs up in the spring. He has fished on Scottish lochs by moonlight, with red deer drinking only yards away; he has become fascinated by the minutiae of river life. “You don’t have to carry empty film cases in your pocket to put flies in you don’t recognise; you don’t have to catch a mayfly to find out if it’s male or female; you don’t have to grub about by the river turning over stones to see what’s living under them. You don’t have to do those things, but it’s all there if you want it.”

Roger Beck, Nettle Meadow, West End, Ampleforth, York Y062 4DX. Tel: 01439 788483; mobile 07711 833433. E-mail: beckfisher@hotmail.com