Exacting Ireland boss Joe Schmidt's almost constant battle is to keep his devilish detail under wraps, to protect his coaching formula from prying eyes.

Exacting Ireland boss Joe Schmidt's almost constant battle is to keep his devilish detail under wraps, to protect his coaching formula from prying eyes.

But every now and then he lets his avuncular demeanour slip, just slightly, to offer a more revealing portrait of a smiling mastermind at work.

Former schoolteacher Schmidt's shtick for fending off enquiries into Ireland's inner workings starts with a smile, then quickly spreads to misdirection.

Distract them with kindness, then nudge the answer to the question towards a catalogue of future opponents. By the time Schmidt has finished listing the weekend's most threatening players, sometimes the inquisitor has lost their train of thought.

Just another impressively efficient tactic from a taskmaster coach who has built this Grand Slam-winning Ireland team entirely in his image.

And the result is that precious few kernels of his intellectual coaching property escape Ireland's "bubble", as he so often terms the national side's set-up.

In the bowels of a snow-capped Twickenham, with all Ireland's Six Nations foes laid waste however, Schmidt had no option but to reveal a golden nugget of truth that underscores his fervour for mining rugby's minutiae.

Ireland's second try in Saturday's 24-15 win over England that sealed just a third-ever Grand Slam came courtesy of a classic Schmidt training-ground ruse.

Like a Gridiron coach with a 300-page play book, Schmidt dreams up set moves, then tailors them to unpick specific opponents' defences.

So when Tadhg Furlong took a pass in midfield on a runaround off Johnny Sexton, and sent Bundee Aki crashing through England's defensive line, there was no ounce of luck.

Ireland had just pulled off the most ludicrous of all lineout back peels, because once upon a time a tighthead prop had no business acting like a centre off a set-piece. CJ Stander finished off the break, and Ireland were en route to a Grand Slam to stand alongside the triumphs of 1948 and 2009.

There are no limits to Schmidt's invention, this so very necessary cornerstone of his coaching.

That restless relentlessness has carried him to greatness within Ireland.

Ireland reserve hooker Sean Cronin last week hailed Schmidt as the world's greatest coach. The former Bay of Plenty boss now has the springboard to prove just that at next year's World Cup.

"We played the identical move against England three years ago in Dublin, and Robbie Henshaw went through and fell over," said Schmidt, referring back to Ireland's 19-9 Six Nations win over England in 2015.

"They are the only two times we've played it. The way they come up defensively we thought it would work again."

Only in the wake of a Grand Slam triumph would Schmidt have lifted the lid, just a crack, on his coaching mindset.

"Sometimes you get double jeopardy, you think 'they might do this, we might do that'," Schmidt added, of the move that led to Stander's stunning try.

"And then they think, we think...I give up, then."

But he does not give up, he does nothing of the sort.

Online Editors