Because he’s six foot five – it’s always spelled out in imposing imperial measurements – and barrel-chested with hands like Christmas turkeys, there’s very little that can stop ex-military cop Jack Reacher meting out his form of brutal justice.

Deadly assassins, neo-Nazis and army snipers have all failed.

But there’s one person guaranteed to bring avenging hero Reacher to a halt.

Jane Grant, the wife of New York-based British author Lee Child, 64, whose books have sold more than 100 million copies.

“She’s completely supportive and takes my writing very seriously, but she doesn’t quite understand that the bubble is a very tenuous thing,” Child told The New Daily, on the phone from a Brisbane hotel during a PR tour to promote the 23rd Reacher novel Past Tense.

“If she walks by and asks, ‘Do you want a cup of coffee?’ which is a lovely thing to say, obviously, it rips you out of the zone and it takes you 30 minutes to get back into it,” Child said, whose real name is James Grant.

As gripping, gritty and bloody as ever, Past Tense sees the hulking avenger mixed up in the trials of two unfortunate Canadian tourists while he’s hunting for remnants of his late father’s early life.

Close to home, Child’s retired civil servant dad died not long before the book was written.

“He’d been in very bad shape for the last four or five years, and all the grieving had already happened, because he was basically gone except his heart was still beating,” the author said.

“When he did die, I wasn’t upset as such, but I was tempted to look back over his life.”

Describing Past Tense as a rumination on how well can we ever hope to know anybody else, the one thing Child said he was sure of was the world is a dark and dangerous place. It’s something Reacher has always known.

“People used to get genuinely outraged when I’d write about the FBI being corrupt or the government cheating or something like that,” he recalled.

“They had a naïve trust. Now they’ve totally come round to my way of thinking. I was right all along. This is a cynical and bleak world.”

A long way from how broke he was when he penned the first Reacher novel Killing Floor (1997), after losing a gig working in British TV, he’s still as driven. Child pumps out at least one book a year, in between Jane’s coffee distractions.

One book is sold every nine seconds somewhere in the world, according to reports.

“You can’t necessarily grow any more talent, but you can certainly outwork everybody else,” he offered.

Moving to New York 20 years ago, just after second book Die Trying (1998), kept him grounded.

“I love its energy, its buzz, and also it’s incredibly reassuring, because the city is just a big, brutal place. It doesn’t give a s–t who you are,” he said.

“There’s always somebody bigger than you.”

Talking of size, Tom Cruise’s dumping as leading man in the Reacher movies (2012’s One Shot and 2016’s Never Go Back) made headlines last week, with his stature apparently the issue.

This guy: Lee Child with Tom Cruise in Louisiana in October 2016. Photo: Getty

Child, whose last tour date was in Melbourne on Wednesday night, acknowledged the casting of the veteran Hollywood action man, 56,  was a “spectacular mismatch” for readers.

“He’s a really terrific guy, a great actor, and he’s great at storytelling, obsessed with every element, so working with him was an education,” he said.

“But the fans have been grumbling so hard and so long and I’ve got to put them first.”

With plans afoot for an ongoing TV series, Child laughed as he confirmed whoever they choose, “You bet he’s going to be the biggest mother f—-r you’ve ever seen”.

Will Reacher ever tire of the good fight? Unlikely. Child insisted the “knight errant” will never even get a cold.

“I’ve lived like Reacher sometimes, just for the fun of it, wandering around with nothing, staying in cheap motels,” he said.

“It is tiring, but you can’t really afford to show that in a story that’s basically subsisting on myth and legend.”