ONE effect of the World Cup cycle is to make sure that the coaching merry-go-round stalls for 18 to 24 months before the tournament and then goes into overdrive to catch up once it is all over.

That’s certainly the case this year, where Scotland and England will be the only Six Nations sides to retain their head coaches and for both of them there are going to be changes among the support staff.

At Scotland it was all sparked by events in Australia with Dave Rennie, the Glasgow Warriors head coach, moving to take charge of the Wallabies after Michael Cheika decided not to reapply for the job. He may take Matt Taylor, the Scotland defence coach, with him and will be replaced by Danny Wilson, the forwards coach.

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This works out well for Gregor Townsend, the Scotland head coach, who needs to show he is willing to make changes after a disappointing World Cup, which ended at the pool stage for only the second time. History shows that if a team fails to meet its targets and the head coach still keeps his job, he is likely to sacrifice his assistants – as happened in 2008, when Alan Tait and George Graham left after World Cup defeat by Argentina was followed by a disappointing Six Nations, and in 2012 when Graham Steadman lost the defence role to Taylor. If Townsend’s assistants go to new jobs, he gets to shake things up but make it look as though he has been forced into it. Win-win.

Rennie, who has a considerable pedigree in New Zealand, where he took the Chiefs to the Super Rugby title in his first two seasons in charge, knows that the Australian public look at four underperforming Super Rugby franchises but still expect their national coach to produce a winning team from the scraps being offered up.

Worse, they are expected to do it the “Australian Way”, which means plenty of flashy handling and back play – conveniently forgetting that their only World Cup title since the game went professional was earned by being the first national side to bring in a rugby league defence coach.

It’s a tough ask, but Rennie is big on team culture and has shown at Glasgow that he knows how to take a team full of attacking talent and add a hardened, gnarled edge without sacrificing too much in the way of flair. Last season was the first where Glasgow reached the knockout stage in two competitions, the PRO14 and the Champions Cup. There is still a gulf between them and the likes of Saracens and Leinster but he has a platform to build on so that he can hand the club over to Wilson in a healthy state.

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That alone will be something of a novelty for Welshman Wilson, whose previous spell as a club head coach at Cardiff Blues was marked by on-field progress despite off-field problems that eventually persuaded him to hand in his resignation.

He took over a team that had finished 10th in the PRO12 the year before and had not finished in the top half of the table for five years. In three seasons he took them to Heineken Champions Cup qualification and silverware in the Challenge Cup.

Where the doubts arise is when people recall the job he will leave after the Six Nations – as Scotland forwards coach. The World Cup was poor in many respects and the forwards played their part in that, particularly in their surprisingly tame showing in the opening game against Ireland.

It means Wilson will meet some resistance from outside the camp – most saying that if Glasgow could not land another big name, they should have gone for a Scottish coach – but the players seem to like and respect him and that is what is really important.