He admits he was a bit out of practice. "I had been a bit crook, which happens at my age, so I hadn't been training much the last few years," says Bill.
"But after working Baldy last Wednesday I went inside and told my wife I thought we should have a wee bet on the horse this week. I also told her to keep it quiet, because I didn't want every bugger knowing."
There would have been plenty of other horse trainers around the world having similar conversations last week.
But not may of them are 93 years old. Or train on 300m tracks they built themselves, a track 100m shorter than an athletics track and one-third or even one-quarter the size of a normal harness racing training track.
And Bill was right. Iwi Baldy broke his maiden status in a $12,000 race last Friday, with Bill pocketing almost the entire winning stake as owner, trainer and breeder.
Still, he had one regret.
"I had a $50 note in my pocket and went up to back him because I was sure he could win.
"But I chickened out at the last minute and only had $20 to win and $30 a place on him. I should have just backed my own judgment."
For the record Iwi Baldy paid $5 a win and $1.40 a place.
While 93-year-olds actively training horses every day at 6am is almost unheard of, nothing about Bill's career follows the usual racing script.
Most horsepeople have some family history in the industry or at least a lifelong love of racing. Not Bill. He started training when he was 70.
"I was a farmer and when I retired a neighbour gave me a horse he thought I might have fun pottering around with," he remembers.
"It was no good though but I quite enjoyed mucking around with it and wanted to learn more."
Not easily deterred, he bought another mare, started his own breed and has averaged a winner a year for the past 20 years, usually from around just a dozen starts per season.
That included training an open class mare named Elizabeth Bay, who raced at the elite level against some of the best trotters in Australasia. At the grand old age of 27, she is the dam of Iwi Baldy.
All of these feats have been achieved training from the 300m track Bill built on land left over after he built his daughter a house next door to his own property.
"My track might be small but my horses do all their work on it," he says defiantly.
"Even our fast work. I don't bother taking them to the trials or anywhere else to work, we just do it at home.
That is because Bill doesn't see so good these days. Not good enough to drive Iwi Baldy in the trailer float to Auckland for the races anyway.
"So my son-in-law drove us up last week. I'm happy enough driving on roads I know down here but my reactions aren't sharp enough for the big city."
But there is no stretch of Kopu that Bill knows better than that 300m oval at home so he still does all his own trackwork, driving Iwi Baldy and his two stablemates in fast work.
"I still enjoy it, it keeps me young," he says. "And the young horse I have got out of Elizabeth Bay, he has kept me on my toes because he has been a bit of a mongrel.
"But I am getting on top of him. He just needs a little time."
Sounds like he is with the right man.