Philip Browne, the IRFU chief executive, has admitted that if the deal to bring Johnny Sexton back to Leinster on a four-year international contract with the Union was supplemented by a private backer, then that was merely in keeping with previous commercial deals which marquee players such as Brian O’Driscoll have made in the past.

Sexton has signed a four- year deal with the IRFU to end his two-year sojourn to Paris with Racing Metro at the end of the current 2014-15 season, amid a widespread belief within the game that the deal was supplemented by the businessman Denis O’Brien.

The Irish Times has learned that the Irish and Lions outhalf has been signed up as an ambassador for Topaz, the O’Brien- owned Irish petroleum retail chain.

“It’s nothing to do with us,” Browne told the IRFU’s digital magazine In Touch in relation to any supplementary, private aspect to Sexton’s contract. “At the end of the day, we deal in a playing contract, so he has a playing contract which is the same as any other playing contract.”

Sexton’s basic playing contract with the Union is understood to be around the €500,000 to €600,000 per annum mark, akin to the international playing contracts which Seán O’Brien and Jamie Heaslip signed last season, with the O’Brien/Topaz commercial arrangement rumoured to swell that figure by an additional €150,000-€200,000 per year.

Sexton’s deal ensures he will play his rugby with Leinster until the end of the 2018-19 season amid increasing evidence that the Union have allowed the provinces more flexibility in helping to supplement international contracts.

Similarly, O’Brien and Heaslip are believed to have had their deals swelled by commercial arrangements which, at least in part, were facilitated by Leinster after they successfully stated their case to the Union that having lost Sexton to Paris and Isa Nacewa, Brian O’Driscoll and Leo Cullen to retirement in a 12-month period, they could ill- afford to lose either or both of their back-rowers to Toulon.

Indeed, O’Brien came within 24 hours of joining the current French and European champions, and it is understood that Leinster’s intervention enabled Bank of Ireland to employ Heaslip in an ambassadorial role and thus keep him in the province.

Revealing some of the background to Sexton’s prodigal return, Browne said: “The history behind it is that I had conversations with Johnny in May before the summer tour, and we arranged to meet after he came back from the tour to Argentina when things had settled down. We met up with Mick Dawson (the Leinster CEO) and established what he wanted in terms of coming back.”

“Effectively what we were able to do was put together an IRFU contract which allowed him to come back in the full knowledge that the support structure was still there, that Joe Schmidt wanted him and that Leinster wanted him.”

“There was a lot of stuff in the papers about private money, but that’s his business, that’s between him and whoever is sponsoring him, in the same way that Brian (O’Driscoll) for years had his own commercial arrangements. Johnny is also in a fortunate position as one of our key players with a profile that means he’s in a position to do that.”

“Unfortunately, not all players in the country are going to have the profile to give them the access to their own commercial portfolio. The IRFU contract brought him back and that puts him into the market place for his own commercial programme.”

In addition to being a key player for Leinster and Ireland, Browne admitted that Sexton is “a role model” for the game here in general, “and so it was important to try and bring him back. He took on board everything we said we’d try and do in terms of his career and we came to an agreement for a four-year contract, which obviously had some bearing on things and that all helped with his decision to come back, and we’re delighted that he did.”

Sexton is currently sidelined with a fractured jaw, and while he should be back in time for the autumn tests, his deal to return home will have little impact on his and Ireland’s preparations for the 2015 World Cup in England.

Meanwhile, as expected, the IRFU have confirmed that Neil Doak will assumed the role of Ulster head coach on a permanent basis while their interim head coach for the first few months of the season, Les Kiss, is to resume his role with Ireland as defence coach up until the 2015 World Cup before returning to the province as full-time director of rugby in succession to David Humphreys.