More than four decades have passed since the Brian O'Driscoll of his day lined up for an eagerly-anticipated last appearance against England at Twickenham. The ageing Irish legend on that occasion was a less-than-svelte Tony O'Reilly and, even if the story of his recall in 1970 after a seven-year absence grows taller by the year, it does serve to illustrate how radically the game has altered in the interim.

O'Reilly, by then 33 and better known for his business exploits, had been hastily summoned as a late wing replacement for the original choice, Bill Brown, and duly arrived for the pre-game training session at the Honourable Artillery Club in London in a chauffeur-driven limo. One team-mate suggested his warm-up had consisted of "running twice round O'Reilly" while the captain Willie John McBride felt his best chance of unnerving England was to "shake your jowls at them". Only a few minutes had elapsed before a dazed O'Reilly was lying on the turf, the victim of a stray boot to the head at a ruck. "While you're at it, lads," cried an Irish voice from the crowd, "why don't you just kick his effing chauffeur as well."

Unsurprisingly, England went on to win and O'Reilly limped back to his day job with Heinz. No professional player these days would admit to eating baked beans, never mind running the multinational company selling them. When O'Driscoll, set to win a world record-equalling 139th Test cap, made his debut in 1999 even the concept of video analysis barely existed. Compare and contrast with the modern era, where every metre the 35-year-old runs will be tracked by GPS sensors while chauffeurs now wait outside gyms and physiotherapy practices.

There is a whiff of that generational divide about the duel between O'Driscoll's Ireland and Stuart Lancaster's forward-looking England. Ancient and modern, young and old, are about to collide and neither age group is minded to step aside. It feels, accordingly, like a significant moment in the recent history of both teams, particularly for a home side seeking to put down a marker not just in this year's Six Nations but next year's World Cup. Fail to respond, on a decent surface in front of their own supporters in their putative fortress, and England may have to reconsider their best way forward.

A defeat would also present Ireland with a first Triple Crown since 2009 and inflict a symbolic 100th home defeat on England by all-comers since they first hosted Test rugby at The Oval in 1872. Are the Irish still a better, more seasoned side, or is a golden generation on the slide? "You have to respect people's caps and what they've achieved but, ultimately, it's about us," said Graham Rowntree, the home forwards coach. "Our young guys won't be overawed, they'll be ready. They are hungry and I'd even say they are desperate to perform. We want them to go out there and be fearless."

Factor in the events of two years ago when Ireland were skewered 30-9 at Twickenham and Joe Schmidt's team will also regard this fixture as a vital bellwether. Anyone seeking a reliable form line, however, should be careful about that one-sided 2012 contest. Neither O'Driscoll nor Paul O'Connell were involved, the Irish front row were hamstrung by injury from an early juncture and, because of a postponement in Paris, the visitors were playing their fourth Test in successive weeks.

Only three of the England team – Chris Robshaw, Dylan Hartley and Owen Farrell – survive from that starting XV and, crucially, the now-injured Dan Cole is not around. Remarkably, this will be the first time since March 1975 England have kicked off a championship game at Twickenham without a single Leicester player in their starting XV.

Of more up-to-date relevance is whether England's forwards have it in them to maintain the collective progress they have made in recent months. Rowntree remains confident that Davey Wilson, Cole's replacement, will stand firm despite his recent lack of rugby but Ireland, in addition to their trademark choke tackles, driving mauls and accurate kicking game, have yet to concede a try in this championship. Then again, they have yet to encounter Billy Vunipola's bullocking strength, or a pair of locks in Joe Launchbury and Courtney Lawes who are improving by the week. "We've got two very athletic, intelligent ball-handlers who aren't without physicality," confirmed their team-mate Tom Wood. "We refer to all-court players now, you can't be a one-trick pony in the modern game."

O'Driscoll has always subscribed to this supposed new template. The green chameleon – part visionary centre, part hard-nosed flanker – has never been a one-dimensional type and is not about to start now. There seemed an unshakeable belief within Ireland's ranks they would beat Wales a fortnight ago and it would be a considerable surprise if they tiptoe meekly into town this time. Leinster have already shown Northampton in this season's Heineken Cup what can happen if a home side are slow to settle against O'Driscoll, Cian Healy, Jamie Heaslip and co, although the Saints did extract some revenge in Dublin a week later. Lawes is confident England will be up for it from the outset this time: "At club level things like that can happen. In international rugby it happens far less."

It would, accordingly, be a surprise if either side wins comfortably. Both came very close to defeating New Zealand in the autumn, both were far too good for Scotland, both are highly motivated. England may or may not generate extra positive vibes by climbing off the team bus earlier and promenading through the massed throng of corporate punters in the West car park but they will need plenty of energy to prevent the likes of Peter O'Mahony, Ireland's maul specialist, from dictating events. "We've had a good look at him, funnily enough,"Rowntree said. "That sense of urgency to support our ball-carriers is going to be paramount."

Fifty years have also elapsed since Ireland won at Twickenham by more than six points. Schmidt is as cunning an analytical fox as they come and the new scrummaging laws seem to be suiting Ireland. England are conscious this encounter will potentially shape their season, not to mention their title prospects, and their forwards are well and truly braced. "I hope one day we will look back and say this was a defining moment of this England pack," Wood said.

O'Driscoll may be in far better shape than O'Reilly ever was but the generation game at this level gets no easier. If a youthful home pack can avoid being dragged down a dark alley by the visitors' elder statesmen, there is every chance of a breathless England victory by three points or so.

• This article was amended on 28 February 2014. An earlier version referred to a bell-weather, rather than a bellwether. A wether is a castrated ram and one wearing a bell, leading the flock, is a bellwether.