The cat's ashes and the Bible were placed in the casket with him and Harbour City Funeral Home director Simon Manning said Mr Grant would be buried in his native Stratford.
Not a lot is known about Mr Grant but Mr Manning, after being approached by the Catholic Church to take the service, did his best to uncover what he could.
"If we can find family, even if they are distant cousins, it's nice to be able to involve them if they want to be involved."
While he didn't find any relatives, Mr Manning uncovered details about Mr Grant's early life and found he had a stint an orphanage near Stratford.
He was 12 when his mother Betty died and just 9 when he lost his father, Jim.
It's possible Mr Grant senior was killed in a house fire but Mr Manning couldn't find any newspaper or other records to corroborate that.
At 15 Mr Grant joined the post office and spent the next 50 years there, working in Te Aro, Trentham and finally the Wellington Railway Station.
It sounds lonely and sad, but his decades in the funeral trade have taught Mr Manning to keep an open mind.
"The important thing is not to judge him or his life. If he chose to live that way it's not sad for him, what he chose to do."
This morning's funeral service was held as part of Sunday mass, in front of 200 to 250 people.
"James was in their parish. I don't think he attended church there but when they saw the original report he'd been found, they rang and said they'd like to offer to have the funeral at the cathedral," Mr Manning said.
"That's how things started really, the priest in charge, Father James Lyons, said why don't we combine it with Sunday mass and try and engage their parish community with a little bit of reality about how people live and how they die."
Mr Manning said today's service was a "very nice funeral" and included a reminder to think of others.