A missing Christchurch man who police are working to find posted a cryptic note on his front door before he vanished, neighbours have said.

Stewart Willis, 63, was reported missing three weeks ago and has still not been found.

Police say they have concerns for his welfare.

He was last reported to have been sighted at his home on Colombo St, in the city’s central suburb of St Albans.

Willis lives in a block of four flats, in a small unit halfway down a driveway that leads to a bustling city road. His car is still in the driveway.

A neighbour spoke to the Herald this morning and described Willis’ chatty nature and the positive engagements they’d had with him.

Willis was last reported to have been sighted at his home on Colombo St, St Albans. Photo / NZ Police

“We’d talk very often, he’d sit outside on his front porch and drink his morning coffee,” said Thuya Thuya, who lives in a house at the end of the road.

“If something bad happened in the news, we’d talk about it. If you were needing help, he’d help you - he was a friendly man, a happy man.”

Thuya understood Willis had lived at the property for nearly 10 years.

He didn’t have any visitors and generally kept to himself outside of their chats.

About a month before his disappearance, Thuya said he’d noticed Willis acting differently from how he normally engaged - he didn’t want to talk and seemed “distracted”.

Around the same time, a white sign was allegedly hung on his front door with the word “Farm” written on it.

The sign has since been removed.

Another neighbour, Harmeet Singh, whose unit connects to Willis’, said the man lived alone.

“He’s quite quiet, whenever he sees anybody he would say ‘hello’,” he said.

Willis was understood to have lived at the property for nearly ten years. Photo / NZME

Earlier last week, officers visited the units and asked nearby residents if they’d seen Willis. Thuya noticed somebody visiting the home two days ago, appearing to check the property.

“It might have been a landlord,” he said.

Willis is understood to have worked at a Christchurch-based concrete company as a truck driver. His company declined to comment on the search.

“I’m left thinking ‘where has he gone?’. I don’t understand - but I’ve lived here for six years already but we always thought he was okay,” said Thuya.

Police have asked anybody who has seen Willis or has information of his whereabouts to call police on 105, and quote file number 230807/7610.