Ever since 2004, the choice of Ireland’s captain has been largely self-evident. In a nutshell, for all but one of the last dozen campaigns, it was either Brian O’Driscoll or Paul O’Connell. End of debate.

But for the first time since O'Driscoll made his debut against England at Twickenham in 2000, Ireland will have neither of their two outstanding players and leaders of the professional era at their disposal. O'Connell would make his debut against Wales in 2002, and apart from O'Driscoll being ruled out of the 2012 tournament, and O'Connell for the 2013 Six Nations, they had played some or all of each championship since then.

O'Driscoll assumed the captaincy full-time after Keith Wood's retirement after the 2003 World Cup, and when he was sidelined for the trip to Paris in 2004, his stand-in as captain was O'Connell. And so this scenario remained in place until O'Driscoll was ruled out for the entirety of the 2012 tournament. Again O'Connell stepped in as captain, and when he was injured for the final two games, Rory Best assumed leadership of the team.

The one exception was in 2013, when Declan Kidney surprisingly retained Jamie Heaslip as captain from the November series in the absence of O'Connell but despite the return from injury of O'Driscoll. One win in an injury-ravaged campaign saw Ireland finish fifth and Kidney be replaced as coach by Joe Schmidt. He in turn made O'Connell captain for the last two Six Nations.

In all, O’Driscoll was captain for Ireland’s three Triple Crowns from 2004 to ’07 and the 2009 Grand Slam, with O’Connell captain for the last two Six Nations title successes; a phenomenal return from 11 campaigns with one or other as captain.

In his Irish record of 83 games as Irish captain, O’Driscoll had a 63.25 per cent winning ratio. O’Connell comes third on this list of Irish captains, behind Keith Wood, with 28 games, and a winning ratio of 62.50 per cent. Of all the Irish players to have captained their country 10 times or more, only Karl Mullen (73.3 per cent from 15 games) and Tommy Kiernan (66.6 per cent from 24 games) have higher winning ratios.

O’Driscoll and O’Connell also captained the Lions in turn, in 2005 and 2009, and in the fall-out from losing their twin towers, there was always likely to be a hell of a void. Indeed, Carton House must have felt a little different when the 50 or so players were called in for yesterday’s pre-Six Nations get-together.

Yet when the players were asked to submit a list of names as potential heirs to the captaincy throne, it says something about the core of leaders within the squad that they would have had no problem submitting at least five likely candidates.

Leading choice

Heaslip, at face value, would appear the leading choice. He has captained Ireland 12 times, up to and including the World Cup quarter-final against Argentina last time out. He was also often Schmidt's go-to alternative to Leo Cullen at Leinster.

Although Best’s four games as Ireland captain pre-date Schmidt’s tenure, he is another highly valued member of Ireland’s leadership group and was arguably Ireland’s most consistently effective performer at the World Cup.

Ever since O'Driscoll was relieved of his captaincy of Leinster, leading both province and country was deemed too much to ask even of O'Connell as well. As Ulster's captain, it would be asking plenty of Best, but perhaps an arrangement could be reached with Ulster to lighten his load. With 89 caps, he is now the most experienced player in the squad, although against that, at 33, he may not be a long-term choice.

Johnny Sexton enjoys a fruitful coach-player relationship with Schmidt, has innate leadership qualities and indeed, is the chief strategist in the squad. Asking him to captain the team would run the risk of placing too much on his plate, but one ventures he would relish the role and it would certainly be an interesting choice.

Scrumhalf is a position which involves a fair degree of leadership and interaction with referees, and Conor Murray is another nailed-on first choice when all are fit and well. In accumulating 42 caps in five seasons, Murray has assumed more and more responsibilities for province and country, captaining Munster on occasion, and at 26 would have every chance of completing a four-year cycle to his third World Cup in Japan in 2019.

Apart from O’Connell, Heaslip and Eoin Reddan, who captained Ireland against Georgia in November 2014, the other player to have led Ireland under Schmidt is Seán O’Brien, in the World Cup warm-up win over Scotland last August.

One ventures he would be a popular choice across a broad spectrum of Irish sports supporters. At 28, he has long-term credentials and is a high achieving and demanding figure.

Case history

As Shane Horgan noted on Second Captains yesterday, one of the advantages of having an openside flanker as captain is that their status and dialogue with referees conceivably reduces the risk of them being penalised and yellow carded. Certainly the case history of Richie McCaw would tend to support this theory.

And, in the absence of a Munster dog of war, with his barnstorming carries, tackles and poaches, O’Brien appears the likeliest to fulfil the role of a leader for whom the dictum ‘do as I do’ readily applies.

As someone who ticks a lot of boxes, recently signing a three-year deal, O'Brien is an interesting dark horse alright. gthornley@irishtimes.com