Paul Gustard does not look like a man laden with regrets. If anything, on a chilly lunchtime in the first week of 2019, he appears happier than he did in almost three years as England’s defence coach. “There will be no green-eyed monster,” insists Harlequins’ head of rugby when asked how he will feel if England come good at this year’s Rugby World Cup. “If they win the World Cup will there be a tinge of disappointment? No.”

Easy to say now, but is he entirely sure? Turning down the ultimate rugby adventure in favour of daily 4.45am starts and commuting around the M25 to Guildford is not everyone’s route to personal nirvana. Then again, Gustard has never been a fan of doing the blinding obvious. Sitting in the bar of the Surrey Sports Park, listening to him fondly recalling the day Dean Richards stubbed out a cigar on his chest on the Leicester team bus, is to be further reminded the 42-year-old has always preferred a life less ordinary.

What ultimately pushed him over the edge with England, however, was the 2019 calendar. Glory might have twinkled in Japan but the family price to be paid, with three children now aged five, three and one, was too high. “I was effectively going to be away from January to November. With England camps you don’t go home. During the last Six Nations I saw my wife Laura three times and the kids twice. I didn’t enjoy the Six Nations last year. Not because we lost, it just didn’t feel the same. I’m happy now because I see my family every night, come what may.”

The other consolation, he argues, is that if England can thrive in Japan he will still feel he contributed to it. “I know I played a big part in three years for that organisation; I gave more than just being a defence coach. I’ve got the highest winning percentage of any coach in English history. All I wish for England is for them to win the World Cup because I’d know I’d helped people fulfil a dream.” As for boosting his own CV should Quins flourish and Eddie Jones’s team fade, that is for others to debate. “There will just be happiness for Eddie. I’d also be happy because winning the World Cup would be positive for the English game – and hopefully a few Harlequins players would be playing.”

It could also be argued that the best outlet for Gustard’s relentless energy – having risen before dawn on Wednesday and driven to Guildford he cycled 35km on the exercise bike before starting work at 7am – is the non-stop club treadmill. His new club go to Newcastle on Saturday sitting fourth in the Premiership with the second fewest tries conceded despite not yet having managed back-to-back victories. A top-four finish and Quins’ decision to recruit Gustard will clearly have been vindicated.

His time under Jones, if nothing else, sharpened him up mentally. “Eddie is the most observant coach I’ve met. There’s no waiting or standing on ceremony. It’s simply: ‘This doesn’t look right. Why?’ That’s the question he asks more than any other. Why? He makes you question everything; that’s the main thing I’ve taken away.”

Quins’ training sessions, accordingly, are now shorter and sharper than anyone else’s – “We are more intense than most clubs” – and unprecedented efforts are being made to improve their poor away record. Gone are the days of relying on “lucky” underpants; the coaching staff now collate statistics to identify which players, over time, perform best in pressure situations away from the Stoop. Selection is then tweaked accordingly.

Having previously brought live wolves into the Saracens dressing room to stress the value of a pack mentality and organised for two Apache helicopters to land on Quins training field to help encourage an adaptable, military-style mindset, Gustard makes no apologies for going the extra mile. “I’m not a conventional coach because I’m not a conventional human being. I do things a little bit differently. I’m not a one trick pony: it’s not just about getting a wolf in. As a coach you’re essentially a teacher as well as a salesman. Can I get people to buy in? Everyone’s got knowledge, it’s about how well you transmit that information.”

As a north-east lad, brought up in a hamlet just outside Blaydon on the road to Consett and the son of the prolific former Gosforth winger Steve Gustard, this is also a personally significant weekend in other respects. Gustard was born and educated in Newcastle and was taught plenty by Richards during his time at Leicester. “I remember myself, Martin Corry and Lewis Moody practising mauling in training. Dean had come out to watch: the next thing we knew he had taken his teeth out, picked the three of us up – and we weren’t small blokes – and just ripped the ball off us. It was fucking embarrassing.”

There was also the time the Tigers clinched a league title at Bristol. “I remember on the way back being pinned down by Dean and Darren Garforth. He ripped my shirt off and started stubbing me with a cigar. He was laughing away but he’s a good man really, Deano.” Winning in Bath during Gustard’s first season remains another vivid memory.

“There was a favourite bar where Dean liked to go, mainly to take the shit out of the Bath fans. We were a bit raucous and this huge bloke comes across saying: ‘Richards, I want to arm-wrestle you.’ Dean goes: ‘I am too good for you, you want Austin Healey.’ Little did this monster know Austin was an unbelievable arm wrestler. They did one arm – boom, straight down – then the other, at which point Austin dropped the nut on him. It was like the wild west.”

Different times. In the modern era coaches crave iron discipline and having banned Dave Ward for treading on Wasps’ Thomas Young last weekend, Gustard wants a cleaner contest in the north-east. “One of our mantras is that we want people to come and watch Harlequins and say: ‘That’s a tough, competitive, resilient team but they do it right.’ The big thing for us now is wins on the road. If we can’t get them we’re going to be in the shitfight with everyone else.”

If he is nursing any England withdrawal symptoms, he hides them well.