Leo Cullen and Stuart Lancaster at Leinster - it shouldn't work but does Cullen deserves credit for making marriage of convenience work wonders for Leinster

The list of coaching double acts in sport is a short one and it is rare to find success when a club, county or country appoints a duo to head up their management.

Top-down hierarchy is the accepted norm in elite sport and success is usually associated with one strong leadership figure, often assisted by an able deputy but always the boss.

Mention of co-managers evokes memories of Rob Evans and Gerard Houllier's ill-fated spell at Liverpool or Kevin McStay and Fergal O'Donnell's brief stint at Roscommon.

Memories of Leinster and Munster's successes in the European Cup bring forth the names Kidney, Cheika and Schmidt; but if the eastern province deliver a fourth title by beating Racing 92 on Saturday the credit will be spread between the two men at the top of their tree.

Indeed, the Bilbao final will be contested by two teams with unusual coaching tickets. The Parisians are led by the two Laurents - Labit and Travers - who have led two different clubs to the French title, while Leinster are led by their head coach Leo Cullen and senior coach Stuart Lancaster.

When, after one difficult year in charge, Cullen picked up the phone and dialled Lancaster's number there were those, including your correspondent, who feared he was signing his own coaching death warrant.

The former England coach was damaged goods after the 2015 World Cup, but as well as that baggage he brought with him a bigger reputation and a much larger profile than the new coach he was, nominally, assisting.

Replaced

He was, at the very least, a No 2 and a half and after a couple of months it became clear that his remit extended far beyond the duties of Kurt McQuilkin whom he replaced on Cullen's ticket. An absence of ego has allowed Leinster to thrive under Cullen's watch.

Since they shared the top table at Lancaster's unveiling, he and his senior coach rarely appear in public together but their working relationship appears to be strong.

Cullen's collaborative approach is working wonders, Lancaster has designed the unstructured attacking game-plan, manages the defence and takes the review sessions.

The lineout is Cullen's domain, while he also fronts pre- and post-match press conferences, deals with selection issues and handles the often strained relationship with the IRFU along with head of rugby operations Guy Easterby.

While John Fogarty, Girvan Dempsey and Emmet Farrell all assist with the coaching, there is a clear demarcation between the assistants and Lancaster who is a far more influential figure.

The players rave about his input, he gives detailed and thought-provoking interviews that tend to avoid direct reference to the 2015 World Cup experience which remains an open wound, but delve deep into coaching philosophy.

Cullen's public persona is far more reserved. Difficult questions are met with a knowing smile and the straightest of bats. Even the simplest of queries are met with a raised eyebrow and a long pause before a guarded answer is forthcoming. He is the perfect foil for the hype surrounding his team.

In his three years in charge he is yet to grant an extensive interview, preferring instead to let his side do the talking. Profile is not a priority for a man on the cusp of his own piece of European rugby history this weekend as he bids, along with Travers who was on the 1997 Brive team, to become the first man to win this tournament as a player and a coach.

Already the only man to captain a team to three European titles, it would be a remarkable achievement but mention of it is likely to get a short-shrift in the build-up to the game. "Our styles are very similar, we are very similar in terms of personality," Lancaster said on Monday. "I don't think either of us need to, or want to, be front and centre all the time so Leo is happy for me to lead on stuff, and I'm happy for Leo to lead on stuff.

"He's got very high integrity and very good leadership qualities. I think you saw that as a player, you would have seen that a lot more so than me. I think he's got great integrity, he's got unbelievable work ethic and he's very good on the managerial side of things.

"So the planning on the day-to-day, week-to-week and he's very honest with the players."

That attention to detail took Cullen to Bilbao last week, where he checked on the team hotel and the stadium arrangements to ensure all was in order ahead of the biggest game of his tenure.

A young coach pitched into one of the biggest club jobs in the game ahead of time after Matt O'Connor was sacked in 2015, he has been forced to learn on the job and make mistakes in a very public forum.

His first European campaign was a complete disaster and his most important player publicly slated the club's culture before the season had even come to its conclusion.

By the time it did, they had suffered a humiliating loss at the hands of Connacht in Murrayfield and the province was at a low ebb.

Munster had endured a similar dip when they appointed their legendary former captain Anthony Foley and, after two years, they opted to parachute the vastly experienced Rassie Erasmus in over his head.

Leinster opted to try and support Cullen from within; first by bringing in Graham Henry as a consultant and then by recruiting Lancaster when McQuilkin sadly had to return home to New Zealand for family reasons.

After the loss to Connacht, they decided that a player's past performance would no longer count for much when it came to selection and when Rob Kearney found himself on the bench against Castres last season, it was a sign that they were staying true to that policy.

The full-back's resurgence this season is down to a number of factors, most notably a clean run without injury, but the message had been delivered that reputation was no longer enough to get in the team.

Young players have been backed to perform in big games and have rewarded the faith with results and, having guided his home province to last year's semi-finals, Cullen has them back at the final stage now.

If they complete the job, he is unlikely to be front and centre of the celebrations. On the three occasions he captained the team to the European title, he shared the lifting of the trophy with a team-mate: Chris Whitaker in 2009, Shane Horgan and Gordon D'Arcy in 2011 and Shane Jennings in 2012.

It was always about collaboration rather than ego and that has followed into management.

The style goes against conventional wisdom and it bucks trends, but it is working a treat for Cullen, Lancaster and a Leinster team on the brink of something special.