Ken MacFadyen wanted excitement, challenges and variety in his working life. Every day was to be different. While he was studying physics at university he considered many possibilities, including the armed forces. But, he says, his altruistic tendencies drew him towards the police almost 12 years ago.

Those same tendencies drew him away from the beat and into teaching two years later. Now, instead of watching unsavoury characters, he sits in his physics lab at Penicuik high in Midlothian, watching children develop. “I wanted to make a difference to society. I wanted to do something that would help people.”

Mr MacFadyen, 34, didn’t rush into the force when he graduated. He pondered his choices carefully, spending time researching all the options before joining the Cumbrian Constabulary. He chose a smallish force where he could learn all-round policing rather than specialise, as many do, in larger forces such as the Met in London. Looking back, he sounds like a man who knew exactly what he was doing.

He believed that, as a policeman, he could influence people’s behaviour - while helping them. He quickly found he couldn’t. “You are just picking up the pieces. In education, you can influence young people through your subject and by helping them develop life skills. In policing, you are dealing with negative things all the time.”

Mr MacFadyen also found the unsociable hours difficult, with only one weekend off in four, and often long hours of overtime. “If you made an arrest you had to see it through, doing the interviews, collecting evidence and statements, and filling out the paperwork,” he says. “You’d get paid for it, but I could never guarantee I’d make it to the pub to meet my friends.”

He soon found that while he was sitting for hours - without a break - observing a would-be thief, his mates were in the pub or out on the golf course. His fiancee, now his wife, Helen, was a nurse, which meant that meetings required precise, almost military planning.

The final straw came when he was attacked by a young man he’d apprehended. The offender was fined pound;50 with 120 hours’ community service. “On the same day, in the same court, someone got a pound;120 fine for watching a colour television without a licence,” says Mr MacFadyen, who received pound;50 in compensation for his injuries. “That was the turning point.”

At the end of his two-year probationary period with the police, he walked away and took up teaching instead. He hasn’t looked back.

But spending that time on the beat and in panda cars did help prepare him for the classroom. “It gave me skills that were extremely useful to have when starting out - the sort of things you usually learn through experience.”

To begin with, it gave him an authority that enabled him to take control in the classroom, and to deal with difficult situations. He found he could defuse a heated situation from day one by simply talking in a calm, lowered voice. He also had administrative and organisational skills - and a nose for investigating that enabled him to sniff out deeper problems.

“Policing was definitely more difficult and more demoralising than teaching. I enjoy teaching so much more. I can help the children by teaching them about science, and other transferable skills such as teamwork and co-operation. That’s a real challenge.”

So Ken MacFadyen has his excitement, variation and challenges. And the McCrone report means that, working in Scotland, he only has to put in an official 35-hour week. Plus he has every weekend off, giving him more time to be at home with his wife and two-year-old son, Callum.

He reckons he made the right decision in the end.