"We were delighted when we heard the message last Friday. It was a great way to end the week. It was just fantastic to get to the end of the week and find that they were willing to make this generous gesture.
"It just shows what sort of strength there is in the Masterton community."
Mr Stewart has a strong family connection to the school, being a former pupil and the father of a current pupil - his daughter Maddie.
He was alerted to the theft by colleague Cherie Butler, whose daughter Imogen also attends MIS, he said.
"Cherie came to us last week and said the school lost a chainsaw, would we be willing to donate something, and my daughter goes so we've got a connection to the school."
It was not the caretaker the thieves had stolen from, but the children, Mr Stewart said.
"It was our children, it's our connection."