PADDY WALLACE preserves the sanctity of the dressing-room. He maintains the code of omerta. When pushed for names, he laughs. The topic of conversation is the simmering hostility between Ireland and Scotland, its genesis and whether the apparently recent phenomenon is anything more than just coaches and players jousting for a psychological edge.

First up, he says the rivalry has been there since he can remember. Secondly, it is just as fierce in the Ireland camp as it is in the Scots – but they might hide it that bit better.

Capped 30 times by Ireland from 2006 to 2012, Wallace only faced Scotland three times, twice in World Cup warm-up matches and the other as a late replacement in a 34-13 Six Nations win in Dublin, 12 years ago.

It makes him no less qualified to describe the scenes inside the Ireland dressing-room in the frenzied, fist-pumping minutes before a match against Scotland. He stood alongside the central characters, he saw the veins bulging in necks, the saliva fly from rabid mouths and heard the shouts from the huddle.

Who were the main protagonists? He does not reveal identities but it is not hard to imagine who he might be talking about. Paul O'Connell would surely be one. Ronan O'Gara is likely another. From today's side, Johnny Sexton is cut from the same turf.

“Captains and coaches,” he laughs. “Big names in Irish rugby who would have highlighted that these guys were out in the press saying they were on a par with us; that feeds a squad's mentality throughout the week when it comes to Scotland. It's an added extra to keep them where they are.”

Of course that same animosity has extended to Wales, whom the Irish face tomorrow, but results have been far less profitable than against the Scots, whom they play in the fourth fixture on March 14.

“I think we have been involved in quite close games with Scotland over the years but we seem to be able to pull something out of the bag against the Scots where sometimes against the Welsh we haven't,” says Wallace. “Wales probably play above themselves depending on their opposition whereas maybe Ireland save their better performances for the Scots. Wales always seem to give us their best effort over the years – that's probably not reflected in the PRO14, where Irish teams are fairly dominant against the Welsh.”

Wallace watched from the sidelines as the 2007 Six Nations match at Murrayfield descended into chaos when a blue-faced O'Gara was trapped underneath a ruck and almost passed out. The then Ireland head coach Eddie O'Sullivan suggested O'Gara had been choked by Nathan Hines in the aftermath of another defeat for the Scots but nothing of the sort had occurred; video replays and an explanation from the Scotland coach, Frank Hadden, outlining how O'Gara had ploughed through the Royal Bank of Scotland on-pitch paintwork, soon cleared that one up.

“I think it was put to bed pretty quickly and Nathan was later a team-mate of all the Leinster boys, he was highly regarded from that point of view. I don't think there was any grudge held [but] it was a niggly match definitely.”

That day brought a rare win for the Scots. Over the past 15 years they have prevailed in just three Six Nations fixtures against the Irish. Wallace believes the more Ireland have won, the more frustrated Scotland have become.

Eventually some poor player coughs up a soundbite for the serried ranks of Scottish rugby journalism about how this is Scotland's time, about how Ireland will finally get their comeuppance. The quotes would go on a wall, the newspaper article pinned up like a declaration of war and every man there was urged to read it.

Wallace says Ireland's players already knew they had the beating of Scotland's, but this ritual was about securing the psychological advantage.

“I wasn't coached by Joe Schmidt but he was the master of finding anything [in a newspaper], any flippant remark, anything that he felt could give them an extra couple of per cent of focus, or performance from the guys, he would be looking at. On the flip side of that, the control that he would allegedly put on his players in the media and not saying the wrong thing, not reciprocating and passing that fuel over to the other side. The Scotland-England thing is something I have struggled with in the past. They are giving their opposition fuel all the time. It's not necessary. You're stoking the fires and Joe was always very guarded about doing that.”

So when did the simmering pot start to boil? Wallace recalls regular meetings in the PRO12 and PRO14 during his Ulster days that fostered a competitive edge which spilled over into the international arena. Infamously it brought rancour in the shape of a series of spicy encounters between Munster and Glasgow in the PRO12 with the Scots winning semi-final and final matches in 2014 and 2015 respectively. The bad blood carried into angry pool stage matches in the 2016/17 Champions Cup, in which Munster prevailed.

The most infamous game of the lot came in 2017 when Munster acced Glasgow – and Ryan Wilson in particular – of targeting scrum-half Conor Murray's standing leg as he box-kicked away from a ruck. That same year, the Ireland bus was redirected away from Murrayfield by Police Scotland and Schmidt's squad arrived 15 minutes late. Ireland might as well have gone on a sightseeing tour of Edinburgh and were so slow to start that they lost 27-22 and later cried foul play.

“I noticed it in Gregor's [Townsend] last few years [at Glasgow]. Glasgow and Ulster were in a couple of knockouts together. There was a developing niggle, just through competition and success. It was always going to accentuate the competitive edge, the more familiar they are, the more scores to settle.”

Now 41, the veteran of 189 appearances for Ulster works as a financial advisor these days, but Wallace has had the benefit of regular media work for RTE, BBC and Premier Sports to provide him with an overview of how the rivalry has grown further.

“Scotland should be closer. They have been ultra-competitive with the Irish provinces for a number of years. I don't know what the issue is, where Scotland seem to not translate that, but they obviously deem themselves on a level with Ireland based on [the PRO14] and maybe they put too much pressure on themselves, maybe Ireland are just able to find another gear whenever they play Scotland. I can't put my finger on why that is. You've got plenty of world-class players.”

One of those is Finn Russell and Wallace, an outside-half who converted to centre, is an avowed fan.

“I just love his mentality for how rugby should be played. He's found a great landing spot. He was given that freedom at Glasgow but he has been propelled to that next level being surrounded by so many world-class players at Racing and it's a joy to watch [him]. Finn has a swagger but not for one second would I say that Johnny Sexton doesn't have a swagger. With Finn and the plaudits that he gets for his play, that just fuels the likes of Sexton as well because at the end of the day it's all about winning, it's not about how you do it.”

For all his talking up of Scotland, Wallace expects this year's tournament to play out much the same as the previous two.

“The French are going to be hard to beat,” he adds. “They were pipped at the post last year. England, Ireland, France in the top three again this year – and it's maybe too far to go for Scotland.”