"When the clock has stopped working, for us it's a job we recognise that needs doing, but for Bill it's a complete travesty.
"I've known Bill for four years now and he's very proud and serious about his work. For him it's not about the money, but it's more about maintaining a piece of the city's history," Mr Richards said.
Although Mr Groves can't wind up the clock himself, Mr Richards said the 91-year-old had no problem scaling his way to the top of the clock tower.
"It's quite a task to get up there and the fact that he can still do it at his age is quite amazing really."
Mr Groves was an instrument repairer with the air force during WWII before transitioning to a six-year apprenticeship in watch-making.
"I used to be a wood turner but I didn't want to go to back to a dusty old job like that which is why I thought I'd take up watch-making," Mr Groves said.
After running his own watch and clock-repairing business in Whanganui for 44 years, he retired in Whangaparaoa before moving to Rotorua 14 years ago, where he got back to doing what he loved.
He now repairs people's watches and clocks from home and doesn't see himself stopping anytime soon.
"As long as I can still see and physically get around, I am quite happy to carry on doing it."