According to the old saying, the secret of a happy life is to decide what you like doing and then find someone to pay you for it. If that is the case, Nick Williams should be a happy man, as this former primary headteacher is now touring the country being paid to talk to pupils about his hobby.
Birds and other wildlife have been Nick Williams's passion since he was a schoolboy himself. And since leaving his headship of a forces school in Germany in 1986, he has been taking a series of wildlife roadshows around the country, under the name of Birdwise.
He best known for his ornithological shows and books - and his promotional posters announce: "Nick Williams is the Birdman". Each year this enthusiasm is taken to 250 schools, in a show that mixes storytelling, music and natural history, illustrated by a slide show of his own wildlife photographs. He says that children are quick to share his enthusiasm. "Children can relate to birds, they see them in their everyday lives, whether it's in their street or garden or a park."
Pupils at Clements County Primary School in Haverhill, Suffolk, certainly seemed to respond well to Nick Williams's show about birds of prey, impressed by the size and grandeur of the eagles, cooing appreciatively at the cuteness of the baby falcons and smiling at the owls with their old men's oystery eyes.
As well as displaying his impressive photographs, he also shows how they were taken and how he constructed an elaborate hide that gave him a hidden vantage point over an eagle's nest in Scotland.
Headteacher Olwen Powell says that previous visits by Nick Williams have inspired pupils to maintain an interest in birds, and the school now has a bird table and feeding rotas in operation. Young children have an affinity for animals, she says, and learning about birds has helped them to express this. "It allows children to get involved, to see something they might not otherwise see. They have learned about the risks of ring pulls from cans and not to smash eggs - and they enjoy helping to look after the birds."
The show illustrates how impressive birds can be - that peregrine falcons can fly at 180 miles per hour and that 10 children could fit inside a golden eagle's nest. But Nick Williams also wants to make sure that children are aware of the everyday birds, because even in the country fears about safety mean that fewer children now go wandering through the fields - and that means that fewer children see birds close-up in their natural setting.
He is also keen to make sure that he leaves behind a strong message of environmental responsibility. At the end of his talk he tells his audience of five to nine-year-olds about a duck killed by swallowing a crisp discarded in the water.
And he presses home the message that "we only have one planet, we can't move somewhere else, and we grown-ups haven't made a very good job of looking after it". In talking about the threat to species, he tells the pupils that there were once 20,000 pairs of barn owls in the country and now there are only 4,000.
"Environmental awareness should be part of every lesson - and my shows give children a greater awareness of the need to protect the natural world around us, letting them know that if we're not careful these beautiful creatures might not be around when they grow up."
So how does a travelling wildlife roadshow compare with being a headteacher? "There's a lot of personal fulfilment. It's something I feel strongly about and I want to influence as many people as possible. It's everyone's dream to have a hobby as a job," he says. "I'm now in control of my own life. When I was a head I was being told what to do and how to do it - and many heads feel under pressure."
Next he wants to extend Birdwise by setting up other early-retired teachers in franchises which could take the same slides and stories around schools - contact him if you are interested. As he says, he is glad he "quit while a head".
* Nick Williams and Birdwise, tel: 01778 440500.