"I knew them very well, especially Bill. He was a very keen tramper and we used to go out on all sorts of escapades," Mr Duncan said.
When a large group from Wanganui Tramping Club headed off to the South Island, Mr Bennett asked his friend Nick if he wanted to go - but he said "No".
"I thought I was a bit out of my league. Bill was a really good, hard-core tramper and I was a bit of an amateur.
"I would have been with them [in the hut that night] if I had gone," Mr Duncan said.
On that 1977 trip, four trampers decided to separate from the Wanganui party to spend the night at Three Johns Hut at the head of the Dobson Valley. With Mr Bennett and Mr McLean were 25-year-old Fenella Druce and Craig Benge. There was a terrible storm on the night of January 30, and the four radioed the rest of their party at 7pm - then nothing was heard from them for two nights.
Rangers were asked to look for them and their hut was found in the Dobson Valley, 2135m below the mountain saddle it had sat on. The hut had been blown off the mountain and everyone in it had been killed.
"It was such a big event ... it was all over the news," Mr Duncan said.
Whanganui people were devastated. Mr Bennett's mother asked Mr Duncan to be one of the pallbearers at her son's funeral.
The Four Friends Memorial Trust was formed to remember the event, and Fenella Druce Memorial Hut in Nelson's Cobb Valley was built and named in memory of Ms Druce.
Mr Bowie and others from the same year at Collegiate will be meeting in Whanganui on the weekend of January 27 to 29, also to remember the tragedy. They are to combine with trust members on the Saturday afternoon for a river trip towards Upokongaro on the MV Wairua.
"On the way back we are going to throw a wreath into the river to remember the four people who were tragically killed," Mr Duncan said.
A plaque in the Collegiate Chapel will be unveiled for the four at a service on the Sunday morning. The trust is planning another plaque on a bench beside the river.
Mr Bennett was strong, healthy young man when he died, Mr Duncan said.
"I always thought that Bill would go to Everest if he had lived."