"There was nobody at the station at the time – we were having a little comfort stop.
"That is a lesson that we have learnt. We'll have somebody there all the time now."
McPhee added: "We've not had anything like this happen before."
The train was owned by fellow Hawke's Bay Model Engineering Society member Ken Le Prou.
"I was at the track and it was my train that was taken and derailed," Le Prou said.
"No damage done though, luckily."
The 800m track at Anderson Park, Greenmeadows, will remain open despite the incident every Sunday between 12pm and 4pm – weather permitting.
Police said on Monday afternoon inquiries were ongoing into the incident and no arrests had been made.