The 6ft10ins geography and ICT teacher is quitting his Halifax secondary for Snowdonia, to run an adult outdoor pursuits centre.
Colleagues say Mr Phillips, 34, is a pillar of Holy Trinity Church of England school. He is head of Year 10, as well as the school's National Union of Teachers' representative.
But after more than seven years teaching, the former policeman is leaving.
Workload, initiative overload, and political interference in education have taken their toll and he wants to spend more time with his young family.
"I went into teaching for the same reason as I joined the police - community service. I enjoy working with young people, and still do, but I hate the politics," he said.
"In the past seven years I haven't seen anything get better. I have seen funding cut, my school struggling from one financial crisis to the next, and the Government spending millions of pounds on this and that strategy which doesn't teach us anything we didn't know."
He is unconvinced that last month's workload agreement, which promises teachers half-a-day a week non-contact time, will cut the demands on teachers' time.
And with another child on the way, he also wants to spend more time with his three-year-old daughter, Abigail. "I'm out of the house before my little girl gets up. I get home and see her for an hour before she goes to bed. Doing the things I love with the kids at school, such as taking them pot-holing, means more time away from my family. I have reached the point that my family has become more important to me than satisfying a bunch of bureaucrats."
* The tallest man in the world was American Robert Wadlow, who was 8ft11ins and died in 1940. In England, the record is claimed by 7ft6ins Chris Greener, of Bromley, Kent.