Mick Grindle, 46, who has taught at Trent college, a private school in Long Eaton, Nottingham, for 24 years, only discovered his good fortune when he went to the local shop between two evening meetings at the beginning of term.
"I bought the ticket in July but I usually buy five each week. We were moving house at the time, so I forgot about it. I thought I had won pound;200,000. I went back to the meeting and didn't say anything, I just thought it would help to pay the mortgage off."
But the next day Mr Grindle was told by Camelot that he had won pound;2.2 million.
He broke the news to his wife, Sue, former head of girls' games at Trent, when she came home from her job as PE teacher at Loughborough high school for girls.
"She'd had a bad day and I told her I could change her life, I could solve her problems and she could give up work. She thought I was being stupid."
Mr Grindle will continue to work part-time at the college and his wife also hopes to do the same soon. They are not planning to move but the cash will help with the school fees for their two children who are at Trent. Mr Grindle said the family would still look for bargains and that he would continue to play the lottery using the same numbers.
"Our youngest, Oli, has already spent the money three times over but the eldest, Lauren knew immediately that money changes things. She cried a lot on the day that we collected the money because she didn't want anything to change, she didn't want to be known as the rich kid. We don't want to change our friends, we want to carry on living where we are and to stress the value of money to the children.
"The staff and pupils at Trent have been marvellous and 99 per cent of people have been fantastic," he said.